Documentation work.
Fix incorrect cursor position

When reactivating the cursor its position was updated visually but not
internally which caused glfwGetCursorPos to return wrong values.
Merge pull request #84 from Nibe/cursor-fix

Fixed saved cursor position not being restored.
Added forcing of swap interval on DWM composition.
Fixed window positioning on OS X.
Enabled OpenGL 3.x and 4.x context on OS X 10.9.
Updated references to OS X (previously Mac OS X).
Fixed documentation tag name.
Updated OS X OpenGL compatibility docs.
Moved to auto-updated docs URLs.
Merge pull request #86 from siavashserver/master

Added utility functions for X11 error handler.
Cleaned up X error handler work.
Tagged close flag for use from secondary threads.
Small cleanups and fixes.