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).
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.
HOPKINS: Fix the censorship flag (bug #6591)
SCI: Add note on SSCI 11 FindColor bug
SCI: implement 8-bit color matching SCI1.1 bug
effectively fixes bug #6455
thanks to wjp and [md5]
Merge pull request #513 from BenCastricum/detection_fixes

SCUMM: detection fixes and more HE games
Merge pull request #502 from SpecLad/visual-c++11

COMMON: Use true nullptr in Visual Studio 2010+ and true override in VS 2012+
COMMON: Add reference links for the enabled C++11 features in MSVC
GRAPHICS: Remove some trailing whitespace in surface.h
Merge pull request #438 from fuzzie/tony-565

TONY: Switch to 565 screen format.
AUTHORS: Remove trailing whitespace
README: Remove trailing whitespace
GRAPHICS: Remove trailing whitespace
VIDEO: Remove trailing whitespace
GUI: Remove trailing whitespace
IMAGE: Remove trailing whitespace
BACKENDS: Remove trailing whitespace
COMMON: Remove trailing whitespace
WINTERMUTE: Remove trailing whitespace
TONY: Fix image loading on BE systems again

This was originally changed in commit 43520ce4f3, but it has been
removed accidentally in commit 84fb3e816d