[X11] Match win32 wheel coordinate system

OpenTK uses the win32 wheel coordinate system, where
(+h, +v) = (right, up). XI2 uses (+h, +v) = (right, down)
instead, so we need to flip the vertical offset.

Fixes issue #133 and https://github.com/mono/MonoGame/issues/2686
[Mac] Match win32 scrolling coordinates
[Mac] Add note for higher precision pixel scroll
[Mac] Fix Mouse.GetState() h-wheel

External mice will now report horizontal scrolling in the low-level
`Mouse.GetState()` API. The touchpad apparently creates an emulated
mouse device that does not report horizontal wheel scrolling events.

Touchpad support probably requires a proper multitouch implementation.
Merge pull request #134 from thefiddler/scrollfix

[Mac][X11] Match win32 wheel coordinate system
Merge branch 'develop' of github.com:opentk/opentk into bb10
Implemented BlackBerry display device driver
Removed EglBlackBerryPlatformFactory and merged it with BlackBerryFactory since BlackBerry uses either proprietary graphics OR OpenGL, so keep it standard
Placeholder for BlackBerry INativeWindow implementation
BlackBerry can now get process addresses (eglGetProcAddress)
BlackBerryGLNative now creates a window and cleans it up