Reload all GL state when toggling fullscreen on OS X

[Philip]

On OS X, switching from fullscreen to windowed mode apparently triggers errors like ogl_program_get_uniform_location(shader, "TextureMatrix1") returning negative values, and the textures disappear and everything goes black and grey and sometimes it crashes.

I guess the GL context state gets lost when toggling fullscreen, in which case we need to destroy and reload all our GL objects (textures, shaders, vertex buffers, framebuffers, etc) when switching.

[historic_bruno]

A similar problem occurs on Windows using SDL 1.2 instead of our custom implementation, see #935. Apparently it has been ​fixed in SDL 1.3, so that may be an alternative solution.

[Philip]

As far as I'm aware, SDL 1.3 is nowhere near release (and even further from being sufficiently widely available on Linux that we can rely on it as a dependency), so it may not be a viable solution.

[ben]

In 11752:

Disables broken window resizing and fullscreen toggling on OS X. Fixes #1381. Refs #741