Change clear colour for Intel performance.

THIS BREAKS XNA COMPATIBILITY!

Modern (Sandybridge +) Intel Integrated Graphics chipsets have
a fast clear/blit unit ('blorp') which, at least under Mesa,
can only do fast color clears if all of the channels are being cleared
to either full (1.0 or 255) or empty (0). The default XNA discard
colour, CornflowerBlue, does not have this property. This patch
changes the discard colour to black (0,0,0,255) as this is the colour
likely to be best supported by hardware.

This patch gets rid of a per-clear warning on Intel Ivybride/Mesa 10.0 git
using ARB_debug_output.
Fix for Android memory leak and random null ref exception.
https://github.com/mono/MonoGame/issues/1685
Don't change DiscardColor on DEBUG, fix comment
Merge pull request #2124 from sulix/clear-colour-intel

Change clear colour for Intel performance.
Updated NuGet packages for 3rd December 2013
New NuGet packages published from code version as of this date

Only known issue, Win GL project still referencing SharpDX Raw Input

NuGet releases now 3.1.1-Alpha
Added NuSpec for the Content Processor aligned to 3rd December release
Merge pull request #2109 from Nezz/wp8_touchFix

Finally a fix for the WP8 debug bug
Merge pull request #2148 from DDReaper/NuGet_update_package

Updated NuGet packages for 3rd December 2013
Merge pull request #2129 from groundh0g/develop-1685

Fix for Android memory leak and random null ref exception.
Merge branch 'develop' of https://github.com/mono/MonoGame into develop