Update .gitignore
Update .gitignore

The usual suspects (more examples ans tests, generated headers) and the
documentation updated to the cogl2 name.

Reviewed-by: Robert Bragg <12e9293ec6b30c7fa8a0926af42807e929c1684f@linux.intel.com>

djdeath/cogl,gcampax/cogl,djdeath/cogl-android,gcampax/cogl,gcampax/cogl,djdeath/cogl,gcampax/cogl,djdeath/cogl-android,djdeath/cogl-android,djdeath/cogl