Merge branch 'uifix' into 'master'

Fix UI left, right, etc. calculations

While working on statusbox, I've discovered that:
- absolutely everything dependent adds self.ix, self.iy twice. or thrice. this was masking top= bug, for example.
- right=ui sets right to ui.x, which usually sets an object flying to the opposite side of the dialog,
- top=ui sets top edge to be equal to the top edge of the ui, which is probably not what's desired (see left=)
- bottom=ui has similar problem to right,
- hcenter=ui sends a ui element flying half a dialog width to the right,
- vcenter=ui, likewise,
- and hcenter_left=ui I didn't understand what it's supposed to do.

This commit fixes all of the above, sans the last, and also adds 3 pixels of padding between everything to compensate for buggy yet sometimes desired previous results.