Updated OpenTK.dll to version 1.1-1

Based on git commit 5c8b966e71228f54ab1af292ca10eeaa22b7495f from
https://github.com/opentk/opentk

Bindings:
- Adds OpenGL 4.4 bindings (synced with the March 2014 specification from Khronos)
- Improves startup performance by up to 2.5x
- Reduces GC pressure by to 3x
- Improves runtime performance for `GL.[Get]TexImage*`, `GL.[Get]Buffer[Sub]Data` and similar functions
- Improves OpenGL documentation. Required OpenGL versions and extensions are now listed for each function. These can be used to fix some of the most common crashers reported against MonoGame on Steam (e.g. use of `GL.BindFramebuffer()` without checking for support)

Platform:
- Adds support for Windows 8.x, Windows/ANGLE, SteamOS, Mac OS X + Cocoa, Linux+Wayland/Mir and *BSD
- Adds support for the monolinker, ilmerge and il-repack
- Improves interoperability with third-party libraries (SDL2, VTK, Qt, ...) In this case, monolinker will remove the built-in platform support completely