More notifier and redraw cleanup
- notifiers are not filtered anymore, apart from window/screen notifiers,
they get to all regions.
- fixed drawing of 'action zones' in areas.
- added support for basic multilayer draw, like for action zones now,
and future other area decorations (tabs, region handlers)
check: ED_area_overdraw_flush()
ED_area_overdraw()
- bugfix in UI redraw tags, it was calling region pointer in free'd
data
- added notifier for marker-changed
- added keymap for markers to ipo window
962870b235