Add capability to monitor or prevent window resizes

[Taneb]

Something like:

setResizable :: FreeGame m => Bool -> m ()
getResizable :: FreeGame m => m Bool
getSIze :: FreeGame m => m Vec2
setSIze :: FreeGame m => Vec2 -> m Bool

[fumieval]

Sadly, we can't change dynamically whether the window is resizable.

But I'm making capability to handle resizing, then I can implement getResizable, getSize and setSize at least.

[fumieval]

Added:

getBoundingBox :: FreeGame m => m (BoundingBox Double)
setBoundingBox :: FreeGame m => BoundingBox Double -> m ()

And we can now pass Resizable to runGame.