Blender Git Loki

Fix: Remove UI_BLOCK_MOVEMOUSE_QUIT from popovers

This was causing driver editing popovers to just keep disappearing
whenever you accidentally moved the mouse away, making the popovers
there nearly useless.

After testing with the other popovers we have in other places, I don't
really see why we needed this flag enabled in the first place. You can
still switch between popovers in the topbar by mousing over the others,
and if you want to dismiss without clicking to escape, you can go over a
standard menu instead OR just move back towards the button that spawned it.

Let's just test this out for a while and see how it goes. Maybe we don't
need a more invasive solution here...