Fix misspelling in schema update 1312.

This fixes a misspelling in the schema update to convert the old
per-profile hardware profile setting to a global setting. Users who made
the schema update prior to this commit will have to re-enable the
hardware profiler manually.
Have hardware profiler disable itself when deleting profile.
fix doxygen link and change style to be less prominent
Small refactor of AC3 encoder.

It can now be initialised many times (not that it's ever used that way). Also let FFmpeg allocates the required memory automatically rather than using a fixed size buffer
Make sure we only run one Bonjour registration at a time.

Seems Bonjour isn't re-entrant with some implementations. So surround it with a lock

Fixes #11446
Make sure we delete RAOP device in the thread that started it.

Fixes occasional crash at shutdown
Make sure we delete AirPlay device in the thread that started it.

Fixes occasional crash at shutdown
Remove empty and unused main.h
Fix display of screen presented before main menu

On mac, the screen letting you know to upgrade your database, or making you select a language do not appear when using OpenGL. So use Qt painter at first, followed by using the OpenGL painter for the main menu.
Various fixes to HLS encoder and mythtranscode.

HLS encoder and mythtranscode assumed they were always receiving 16 bits stereo, which is just not correct with current FFmpeg. Modify them so they can convert on the fly the audio data provided as required.
Simplify avformatwriter so it will detect which audio format to use for the encoder ; this should make it more robust should FFmpeg change its formats once again.
Various simplification: store AudioFormat into filewriterbase, instead of bits and sample size
Rename "samples" when "frames" were actually used.

Fixes #11497
Remove deprecated defined() on aggregate

from mythconverg_backup.pl with patch from Jerry.  Fixes #11408.
Merge remote-tracking branch 'upstream/master'