TONY: Switch to 565 screen format.

The old (555) screen format is not supported by some backends.

This leaves the savegame thumbnails as 555 (for compatibility).
AGOS: Give each MIDI track its own loop flag

This is needed because the MIDI resources have their own loop flag
that overrides the global one. This makes a difference for games
that use MIDI both for music and sound effects, such as (limited
to?) the floppy version of Simon the Sorcerer 1.
COMMON: Use true nullptr in Visual Studio 2010+ and true override in VS 2012+

Those compilers support these features despite not being fully C++11-compliant.

<http://msdn.microsoft.com/en-us/library/hh567368.aspx> says that VS 2010
has "partial" support for override. I don't know what that entails and I
can't test it, so I err on the side of caution and only enable it in 2012
and up.
WINTERMUTE: Import subtitle code from WME1
WINTERMUTE: Astyle imported WME subtitle code
WINTERMUTE: Use long-style braces around blocks in imported subtitle code
WINTERMUTE: Use BaseFileManager to load SUB file

Conflicts:
	engines/wintermute/video/video_subtitler.cpp
WINTERMUTE: Take const char in loadSubtitles
WINTERMUTE: Reinstate subtitle loading
WINTERMUTE: Display subtitles in console
WINTERMUTE: Re-enable and use PathUtils for auto SRT detection
WINTERMUTE: Use native C types instead of macros
WINTERMUTE: Add getter for _videoFont
WINTERMUTE: Port actual subtitle display code.
WINTERMUTE: Reinstate CVidSubtitle destructor
WINTERMUTE: Mass ScummVM-style renaming in subtitles code
WINTERMUTE: Declare counters as uint to match Array::size()
WINTERMUTE: Correctly delete _subtitler (which is not an array)
WINTERMUTE: Refactor/Reformat VideoSubtitler::update
WINTERMUTE: Expand subtitles by string table