Input remapping, game avatars, and more fixes

In today's update:

Keyboard/controller input remapping (Options > Controls)
Added additional Steam "Official Game Avatars" (thanks j1nroh!)
Improved handling of corrupt save files. If save is corrupted, backup load will be attempted.
In 2D mode, CPU/GPU usage is reduced when application window is minimized or hidden.
Fix potential crash changing leaderboard view in VR mode.