Support copying tiles from one part of the map to another

[elliotkendall]

We need a way to copy/move sets of tiles from one part of the map to another. I was originally thinking of drag to select and then copy/cut/paste, but I think a Photoshop-style clone tool would be easier to implement and almost as good.

[elliotkendall]

b2bb641c2312f69b0f04c38c92243e47cdece0c7 is an initial take on this. Still to do:

• Support movement of the mouse by more than one tile at a time. Currently this results in an "Unknown direction" exception. Should probably be fixed by making Map.adjacentdirection() and Map.adjacent() able to work on lists of directions, e.g. "to get to that tile from here, go north, north, northeast*
• Support larger brushes. You can currently use a larger brush by selecting it in another tool, but it will make multiple copies of the same source tile
• Highlight the source tile as you draw
• Better mouse cursor, particularly a different one for selecting a source than actually copying
• A better tool icon, ideally similar to the clone stamp in Photoshop-style programs

[elliotkendall]

d449358def3a32e6ea6e80f6d8e2f87adceb8edc fixes moving to a non-adjacent tile in a single mouse move

[elliotkendall]

403fe5bbef27be962887421674b530c7b2dc3094 fixes brush support