Cleanup of video initialization

-Finished moving over to using GLEW extension functions for extension
detection
-Disable WGL_EXT_swap_control_tear and adaptive vsync on AMD hardware
due to bad behavior
-Ensure future AMD cards are detected properly
-Fixed issue where r_fencesync wasn't properly disabled if GL_ARB_sync is unavailable
Add GL_BindFBO to track FBO state/prevent rebinding