Log Message:
graphics: Add imv.

imv is a command line image viewer intended for use with tiling
window managers.

Features
--------

* Native Wayland and X11 support
* Support for dozens of image formats including:
  * PNG
  * JPEG
  * Animated GIFs
  * SVG
  * TIFF
  * Various RAW formats
  * Photoshop PSD files
* Configurable key bindings and behaviour
* Highly scriptable with IPC via imv-msg