Timers: added extra 'event type' argument to call to add a timer:
WM_event_add_window_timer(win, event_type, interval)
This way other timer systems don't generate overhead on the queues.
(button timers were creating unused animation-playback operators)
* API and usage is basically the same still.
* Panels were moved to region level. I first thought of keeping them at area
level, but having them at region level it's simpler to handle events and do
drawing, and also to integrate with view2d. They can still become area level
overlapping regions, if we make a floating (or docked) region that can
contain panels.
* Added back a few panels from the scene buttons for testing.
Issues still:
* The view2d handling and alignment refresh of panels is not correct yet in the
buttons window.
* I did not yet bring back the block handlers system. It was basically a system
that stored which panel was open and where the events for that panel would go.
Just a few functions, but not sure how it fits in 2.5.
* There was a case where dragging panels would not properly remove the window
level handler, but could not redo anymore even though I don't think I fixed
it.
* Some text in the panels goes past the end of the button, that is due to the
checkmark button drawing, not related to this commit.
Other UI code changes:
* Renamed interface.h to interface_intern.h for consistency.
* Fixed some issues with freeing of blocks when they changed due to context.
* uiDrawBlock now takes a context pointer (mostly for block drawextra).
