|SOURCE|
[Common::System::Window]
* Added a pure virtual member function FlushEvents to consume any left over
  events at the users' discression
[Linux::System::LinuxWindow]
* FlushEvents calls XNextEvent until all events have been processed, doing
  nothing other than acknoledging them
Merge branch 'window_manager' of https://github.com/OpenGameDevelopers/ZED into window_manager