Progress indicator updated

A long time ago I created a progress indicator that blended nicely with the info header. However, as someone pointed out, we nowadays have the view3d header at the top of the screen and the python API has also changed a bit. So, time for an update :-)

Code

In the end, I didn't have to change all that much. The main difference is that we now replace the draw() method of the VIEW3D_HT_tool_header instead of the INFO_HT_header and in the update() function we now make sure we tag all VIEW3D areas for redraw instead of the INFO areas.

Some minor changes were needed too, but this affected mainly the test operators: wm.event_timer_add() now has mandatory keyword for optional arguments and of course the way we register operators has changed.

The updated code is available from GitHub.