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
Fixed compile

The addition of Map::tileSize got lost in another change.
Allow dynamically changing map tile width and height
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.
Allow configuring the length of the hex side

This is the length of the straight sides of the hexagonal tile. It can't
be derived from the grid size because it varies depending on the exact
shape of the tile (which is rarely a mathematically sound hexagon).
Added support for changing the stagger indexes

This adds the option of having the even rows shift to the right instead
of shifting the odd rows to the right.
Fixed the hexagonal renderer to be pointy topped

This makes more sense with the current tile coordinates. Changing the
renderer in this way seemed easier than to implement the kind of
staggering required for flat topped hexes. I'll get to that later.
Derive the StaggeredRenderer from the HexagonalRenderer

This fixes the grid rendering of the staggered renderer and adds support
for staggering the even rows instead of the odd rows.

Of course it will do a little bit more work than strictly necessary, but
this should be entirely irrelevant.

Closes #765
Fixed saving of stagger index

Also, only save the hex side length for hexagonal maps, since it makes
no sense to appear for other map types.
Store the stagger direction, even though only 'rows' is supported now

This is mainly because I think 'columns' should be the default (it's
what Tiled Java did and as such may be supported by 3rd party libraries
this way). Hexagonal maps created by this version of Tiled are now saved
with 'staggerdirection' set to 'rows' explicitly.
Updated drive in daily build script
Merge remote-tracking branch 'upstream/master'