Fixed repainting issues when using tiles smaller than the grid size

The small tiles could cause the bounding rect of the brush preview to
become too small for painting its region as tile selection.
Merge branch '0.10'
Added read-only properties for map size and map tile size
Added hexagonal renderer

Only supports one variation of staggered hexagonal for now.

The length of the sides can't be configured yet and is currently
hardcoded to 30.