Fixing various issues that were showing up when trying to snapshot/restore Cube 2:

- RBO's which have been genned but never initialized are now properly snapshotted/restored
- Adding support for GL_FLOAT_RG16_NV
- Fixing size of XVisualInfo struct's ctype desc so the --find command doesn't trigger a harmless but annoying assert in 32-bit builds while scanning through 64-bit traces
- Misc help text fixes