Log Message:
Update to 2.6.0

Changelog:
we're proud to announce the new feature release of darktable, 2.6.0!

as always, please don't use the autogenerated tarball provided by github, but \ 
only our tar.xz. the checksums are:

when updating from the currently stable 2.4.x series, please bear in mind that \ 
your edits will be preserved during this process, but it will not be possible to \ 
downgrade from 2.6 to 2.4.x any more.

#### Important note: to make sure that darktable can keep on supporting the raw \ 
file format for your camera, *please* read [this \ 
post](https://discuss.pixls.us/t/raw-samples-wanted/5420?u=lebedevri) on \ 
how/what raw samples you can contribute to ensure that we have the *full* raw \ 
sample set for your camera under CC0 license!

- Over 1600 commits to darktable+rawspeed since 2.4
- 260+ pull requests handled
- 250+ issues closed
- Updated user manual is coming soon™

## The Big Ones

- new module retouch allowing changes based on image frequency layers
- new module filmic which can replace the base curve and shadows and highlights
- new module to handle duplicates in the darkroom with possibility to add a \ 
title, create standard or virgin duplicate, delete duplicate and quickly compare \ 
with a duplicate
- new logarithm controls for the tone-curve
- new mode for the unbreak profile module
- add mask preview to adjust size, hardness before placing them
- make it possible to change the cropped area in the perspective correction module
- the mask blur has been complemented with a guided-filter to fine tune it (this \ 
works on RGB and Lab color space).
- color balance module has two new modes based on ProPhotoRGB and HSL
- Experimental support for PPC64le architecture (OpenCL support needs to be \ 
disabled, `-DUSE_OPENCL=OFF`)

## New Features And Changes

- search from the map view is now fixed
- visual rework of the lighttable (color label, image kind, local copy)
- an option make it possible to display some image information directly on the thumb
- add optional scrollbars on lighttable, or lighttable and darkroom
- allow each masks of the clone module to have the opacity adjusted
- lightroom import module supports the creator, rights, title, description and \ 
publisher information.
- enhance TurboPrint support by displaying the dialogue with all possible \ 
options (print cancellation will be fixed in TurboPrint 2.47)
- new sort filter based on the image's aspect
- new sort filter based on the image's shutter speed
- new sort filter based on the image's group
- new sort filter based on a personalized sorting order (drag&drop on the \ 
lighttable view)
- collection based on the local copy status
- group image number displayed on the collection module
- new zoom level at 50%; 400%, 800% and 1600%
- better support for monochrome RAW
- add contextual help pointing to the darktable's manual
- better copy/paste support for multiple instances
- add support for renaming the module instances
- add frequency based adjustment for the RAW denoise module
- add frequency based adjustment for the denoise profile module
- all widgets should be themable via CSS now
- add support for configuring the modules layout
- different way to select hierarchical tags in the collection module (only the \ 
actual parent tag, all children or the parent and children)
- better handling of grouped images by allowing setting stars, color label for \ 
the whole group.
- make it possible to apply a preset to a new module instance using the middle click
- new script to migrate collection from Capture One Pro

## Bug fixes

- Fix the color pickers behavior in all modules
- Fix liquify tools switching
- Many more bugs got fixed

## Lua

- No changes

## Changed Dependencies

- CMake 3.4 is now required
- In order to compile darktable you now need at least gcc-5.0+/clang-3.9+
- Minimal clang version was bumped from 3.4+ to 3.9+
- Packagers are advised to pass ```-DRAWSPEED_ENABLE_LTO=ON``` to CMake to \ 
enable partial LTO.

## RawSpeed changes

- GoPro '.GPR' raws are now supported via new, fast 'VC-5' parallel decompressor
- Panasonic's new raw compression ('.RW2', GH5s, G9 cameras) is now supported \ 
via new fast, parallel 'Panasonic V5' decompressor
- Panasonic's old (also '.RW2') raw decompressor got rewritten, re-parallelized
- Phase One ('.IIQ') decompressor got parallelized
- Nikon NEF 'lossy after split' raw support was recovered
- Phase One ('.IIQ') Quadrant Correction is now supported
- Olympus High-Res (uncompressed) raw support
- Lot's and lot's and lot's of maintenance, sanitization, cleanups, small \ 
rewrites/refactoring.
- NOTE: Canon '.CR3' raws are *NOT* supported as of yet.

## Camera support, compared to 2.4.0

### Base Support

- Canon EOS 1500D
- Canon EOS 2000D
- Canon EOS Rebel T7
- Canon EOS 3000D
- Canon EOS 4000D
- Canon EOS Rebel T100
- Canon EOS 5D Mark IV (sRaw1, sRaw2)
- Canon EOS 5DS (sRaw1, sRaw2)
- Canon EOS 5DS R (sRaw1, sRaw2)
- Canon PowerShot G1 X Mark III
- Fujifilm X-A5
- Fujifilm X-H1 (compressed)
- Fujifilm X-T100
- Fujifilm X-T3 (compressed)
- GoPro FUSION (dng)
- GoPro HERO5 Black (dng)
- GoPro HERO6 Black (dng)
- GoPro HERO7 Black (dng)
- Hasselblad CFV-50
- Hasselblad H5D-40
- Hasselblad H5D-50c
- Kodak DCS Pro 14nx
- Kodak DCS520C
- Kodak DCS760C
- Kodak EOS DCS 3
- Nikon COOLPIX P1000 (12bit-uncompressed)
- Nikon D2Xs (12bit-compressed, 12bit-uncompressed)
- Nikon D3500 (12bit-compressed)
- Nikon Z 6 (except uncompressed raws)
- Nikon Z 7 (except 14-bit uncompressed raw)
- Olympus E-PL8
- Olympus E-PL9
- Olympus SH-2
- Panasonic DC-FZ80 (4:3)
- Panasonic DC-G9 (4:3)
- Panasonic DC-GF9 (4:3)
- Panasonic DC-GX800 (4:3)
- Panasonic DC-GX850 (4:3)
- Panasonic DC-GH5S (4:3, 3:2, 16:9, 1:1)
- Panasonic DC-GX9 (4:3)
- Panasonic DC-LX100M2 (4:3, 1:1, 16:9, 3:2)
- Panasonic DC-TZ200 (3:2)
- Panasonic DC-TZ202 (3:2)
- Panasonic DMC-FZ2000 (3:2)
- Panasonic DMC-FZ2500 (3:2)
- Panasonic DMC-FZ35 (3:2, 16:9)
- Panasonic DMC-FZ38 (3:2, 16:9)
- Panasonic DMC-GX7MK2 (4:3)
- Panasonic DMC-ZS100 (3:2)
- Paralenz Dive Camera (chdk)
- Pentax 645Z
- Pentax K-1 Mark II
- Pentax KP
- Phase One P65+
- Sjcam SJ6 LEGEND (chdk-b, chdk-c)
- Sony DSC-HX99
- Sony DSC-RX0
- Sony DSC-RX100M5A
- Sony DSC-RX10M4
- Sony DSC-RX1RM2
- Sony ILCE-7M3

### White Balance Presets

- Canon EOS M100
- Fujifilm X-T3
- Leaf Credo 40
- Nikon D3400
- Nikon D5600
- Nikon D7500
- Nikon D850
- Nikon Z 6
- Olympus E-M10 Mark III
- Olympus E-M1MarkII
- Panasonic DC-G9
- Panasonic DC-GX9
- Panasonic DMC-FZ300
- Sony DSC-RX0
- Sony DSC-RX100M5
- Sony DSC-RX100M5A
- Sony DSC-RX10M3
- Sony DSC-RX10M4
- Sony DSC-RX1RM2
- Sony ILCE-6500
- Sony ILCE-7M3
- Sony ILCE-7RM3

### Noise Profiles

- Canon EOS 200D
- Canon EOS Kiss X9
- Canon EOS Rebel SL2
- Canon EOS 750D
- Canon EOS Kiss X8i
- Canon EOS Rebel T6i
- Canon EOS 760D
- Canon EOS 8000D
- Canon EOS Rebel T6s
- Canon EOS 77D
- Canon EOS 9000D
- Canon EOS 800D
- Canon EOS Kiss X9i
- Canon EOS Rebel T7i
- Canon EOS M100
- Canon EOS M6
- Canon PowerShot G1 X Mark II
- Canon PowerShot G1 X Mark III
- Canon PowerShot G9 X
- Fujifilm X-A5
- Fujifilm X-E3
- Fujifilm X-T3
- Fujifilm X100F
- Nikon 1 AW1
- Nikon 1 J3
- Nikon COOLPIX B700
- Nikon D5600
- Nikon D7500
- Nikon D850
- Olympus E-M10 Mark III
- Olympus TG-5
- Panasonic DC-G9
- Panasonic DC-GX9
- Panasonic DMC-FZ35
- Panasonic DMC-FZ38
- Panasonic DMC-GF6
- Panasonic DMC-LX10
- Panasonic DMC-LX15
- Panasonic DMC-LX9
- Panasonic DMC-TZ70
- Panasonic DMC-TZ71
- Panasonic DMC-ZS50
- Pentax K-01
- Pentax KP
- Samsung NX1
- Sony DSC-RX100M4
- Sony DSC-RX10M3
- Sony ILCE-7M3

## Translations

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