Map resize action gets bundled with the next action in undo/redo

[Skaruts]

I'm having trouble putting this into a sentence, so here's the steps to reproduce:

• resize the map
• draw a few tiles (in a single click)
• press ctrl-z or the undo button once

The result will be that both those actions will be undone, and you'll get back to the old map size, instead of it only undoing the tiles.

Pressing redo will have the same inverted effect.