Implemented a 3d renderer in a separate window.
Lots of improvements and fixes to the 3d renderer.
Switched from pthread to SDL thread support.
Converted 3d visualizer to SDL2.0
Monsters are now rendered in 3d even when not visible on the curses map.
Stored the player position and whether they are driving in a static variable.

This greatly reduces map flickering.
Implemented controls to change the perspective.