Fix missing strings.h
GLRendererRoster: traverse add-ons entries.

* Allow using symlinks to add-ons when developping.
workaround assert in debug mode.

* There is an assert on the _BasicFormat, and it was not set for the
alpha buffer wrapper. Assume same format as underlying buffer.
Dynamically allocate big array.

* This was causing a stack overflow in the Flurry screensaver.
Remove files that are regenerated by the buildsystem.

* And also gitignore them.