Blender Git Loki

Small cleanups in circle select code.

Brought back two hacks from previous code:
- do an 'activate window' for each event that happens. this might be not
needed, see below
- also set glReadbuffer at GL_FRONT for inverse draw

And added an escape out of circle select on INPUTCHANGE, when you activate
another window. So the old hack to activate current window might be
redundant.

Purpose for now; get reports solved about wrong circle selection drawing