AAC fixes (ADTS header) in transcoder and libav muxer
Revert "Makefile.ffmpeg: prefer static linking for x264, vpx, vorbis libs to avoid conflicts with distro"

This reverts commit 8e876995f352b28dc7ca0f5ad683d82e35b38370.

It does not work..
WEBUI: help changes, cosmetics and icon