Update external subs streaming
Formatting
Reverted 150138a
Disable AviSynth/MEncoder by default

It doesn't have the stability of the other video engines and is more for video enthusiasts anyway so they can enable it if they want
Sync UMS.conf default engines string with the one the program uses
Updated changelog
Merge branch 'master' of github.com:UniversalMediaServer/UniversalMediaServer into HDAudioPassthrough
Fixed merge and formatting