gltrace: Add support for NV_framebuffer_blit.
glretrace: Destroy Context only once via glXDestroyContext

Handling adapted from retrace_wglDeleteContext
qapitrace: ignore supporting files generated by qtcreator

When using qtcreator for build/debug, qtcreator creates miscellaneous
helper files that don't need to be seen by git.

Signed-off-by: Lawrence L Love <lawrencex.l.love@intel.com>