This makes eglSwapBuffers() fail with per screen rendering enabled. In
long term, the screencast plugin has to create its own OpenGL context
and capture window frames after a compositing cycle has been performed.
However, it's currently tricky to do because of monitor screencasting.
As things are right now, we can only do 32bit textures for dmabuf (see
gbm_bo_format in gbm.h). This means that we were lying to our receivers
when we had 24bit textures by then giving a 32bit texture instead.
This changes it so we request a dummy texture before starting and if we
are offered one we assume they're available and offer a 32bits stream
directly (i.e. BGRA).
The scripting api is not suitable for implementing all features that
should not be implemented in libkwin. For example, the krunner
integration or screencasting are the things that don't belong to be
compiled right into kwin and yet we don't have any other choice.
This change introduces a quick and dirty plugin infrastructure that
can be used to implement things such as colord integration, krunner
integration, etc.
