Fixed compile

The addition of Map::tileSize got lost in another change.
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).