bump version to 1.90.0-SNAPSHOT
fix some plugin-breaking changes
FFMpeg -> FFmpeg in translations
restore FFMpegVideo.isCompatible cleanup
ensure renderer conf load order is  consistent
remove webfilters hack
FFmpegWebVideo: fix broken executable path
README: add new project member: lightglitch
README: add installation instructions, license and TOC
INSTALL.txt: link to Debian/Ubuntu package installation instructions
fmt + forum link