Added 64bit version of SharpFont.
Disable SDL2 backend on Linux

Workaround for issue #2416
Merge pull request #9 from thefiddler/issue2416

Disable SDL2 backend on Linux
Merge pull request #8 from SickheadGames/font64

SharpFont 64bit
Added 64 bit FreeImage.Dll and FreeImage.NET.dll wrapper.
Built from r3160.
Added FreeImage Public License  file.
Merge pull request #10 from SickheadGames/FreeImageWindows

Added FreeImage binaries
Updated Assimp to work with binary .X files.
Merge pull request #11 from SickheadGames/Assimp

Updated Assimp to work with binary .X files.
Updated SharpDoc from https://github.com/xoofx/SharpDoc 472ff84420e55391d417f1dbc9598d6b53f77129
Merge pull request #12 from Mono-Game/sharpdoc2

SharpDoc Update
Latest CppSharp from fee0f18ee011fa0577ef0073a6b7545531db772c.
Merge pull request #13 from SickheadGames/cppsharp

CppSharp Update
Update OpenTK to 1.1.2

This release contains important fixes for MonoGame:
- New Cocoa backend for Mac OS X
- New Mouse.GetCursorState() API that matches XNA Mouse.GetState()
- New GameWindow.Cursor API that matches XNA behavior
- Improved Linux/X11 input API:
  - Mouse.SetPosition now works correctly
  - non-US keyboard layouts now work correctly
- Improved stability when using the EGL/ANGLE backend
- Improved stability when using the SDL2 backend
- Improved stability when running on a headless system
- Up to 20x better startup performance (5-10ms compared to 150ms)
- Up to 10x smaller allocation graph (~900 objects compared to ~9000)