Updates for Plex Media Server.
Make it build without GTK2.
Fix EOL in Platform.h
Tweak warnings for GCC
Add support for FreeBSD
Remove -Werror since it breaks multiple platforms.
Fix variable name SYSTEM_NAME
Only build x86_64
Fix clip PQ list length (last item slightly cutting off).
Fix PQ home list unwatched indicators not showing. Fixes plexinc/plex-home-theater#1252
Creation of DialogPlexExtras.xml accessible from preplay.

Test version, final will be something different.
A first stab at Extras left panel list in movie preplay.
Show left bar mini player.
Fix stretched background.
Localize title to "Extras". Part of plexinc/plex-home-theater#1256
Some further tweaks to Extras. Part of plexinc/plex-home-theater#1256
Added Container/ListItem.Property(PlexExtras) to debug layer. Part of plexinc/plex-home-theater#1256

Usage:
ListItem.PlexExtras(extra/extras) —> in DialogPlexExtras, for knowing
if a single or multiple extras in the list.
!IsEmpty(Container.Property(PlexExtras)) —> in PlexPreplay, for
showing/hiding the Extras sidebar button
Show Extras button only if any extras exist. Part of plexinc/plex-home-theater#1256
Add Extras count in the title. Part of plexinc/plex-home-theater#1256
Merge branch 'extras'