Log Message:
version 0.5.0
* miscellaneous bug & build fixes
* encoder & decoder speed-ups on x86/ARM/MIPS for lossy & lossless
  - note! YUV->RGB conversion was sped-up, but the results will be slightly
    different from previous releases
* various lossless encoder improvements
* gif2webp improvements, -min_size option added
* tools fully support input from stdin and output to stdout
* New WebPAnimEncoder API for creating animations
* New WebPAnimDecoder API for decoding animations
* other API changes:
  - libwebp:
    WebPPictureSmartARGBToYUVA() (-pre 4 in cwebp)
    WebPConfig::exact (-exact in cwebp; -alpha_cleanup is now the default)
    WebPConfig::near_lossless (-near_lossless in cwebp)
    WebPFree() (free'ing webp allocated memory in other languages)
    WebPConfigLosslessPreset()
    WebPMemoryWriterClear()
  - libwebpdemux: removed experimental fragment related fields and functions
  - libwebpmux: WebPMuxSetCanvasSize()
* new libwebpextras library with some uncommon import functions:
  WebPImportGray/WebPImportRGB565/WebPImportRGB4444