Blender Git Loki

Fix T67265: Status bar is overlapped by workspace layout

The issue was that the screen geometry calculations scaled down the
areas, but the header would become too small. So it would be upscaled
again towards the lower screen edge (where the status-bar is at). Now we
do another pass over the geometry calculations, until all areas fit into
the screen, or until some rather arbitrary maximum is reached.

This fixes the issue for common cases. Extreme cases, with many
vertically stashed editors and a too small window to show all, are still
not too well supported. Blender keeps working but the status-bar is
still overlapped. We could deal with this better but what's there now
should be good enough.