Allow drawing 3x3 or larger patches with the map editor.

[flackr]

Summary

The 1, 3, and 5 buttons on the map editing interface were meant to serve as a brush size to facilitate covering large sections. We should be able to use these to draw larger map regions.

Implementation

Implementing this would be a matter of allowing for a selected "brush size" probably following the pattern set for selected tiles. When generating 'change' events from the paint function in dungeon-client.js, the current brush size should be attached to the change message. In dungeon-common.js this brush size should be respected and the appropriately sized grid around the cursor drawn in.