h264enc for Linux

[microchip8]

ChangeLog for version 8.2.5

- Added support for 30p -> 24p FPS conversion
- Added support for the decimate filter when doing 60p -> 24p
  FPS conversion
- Small improvements to the crop preview code. Should come after
  the user has entered the crop values
- Video file encodings: Use unique default output file based on
  process ID
- Fixed a small bug where h264enc assumes that the $HOME/.h264enc
  directory already exists but that might not be the case, so it
  will fail at making an unique temporary directory. Reported by
  Nathaniel Gray
- Added support for setting the quantization parameter for the
  spp, uspp and fspp postprocessing filters