Blender Git Loki

Merge branch 'master' into soc-2014-viewport_context

setTitle should not be called until the window is valid
note: X11 and WGL do not do as extensive assertions to check if window is valid, so this only caused a problem on OSX

clearing the screen is not visible unless there is a buffer swap. also factored out the GL clear code into a single function

removed options for XInput and XF86Vidmode on OSX because they are not available for XQuartz

fix X11 error where current context was not set for window before calling swap buffers

[Ghost Context Refactor] initial commit based on code review of https://developer.blender.org/D643