Add a dungeon level generator, which:
1. generates an infinite sequence of rectangular rooms within the
dimensions of the level
2. removes any duplicates from that sequence
3. Generates a graph from the delaunay triangulation of the centerpoints
of those rooms
4. Generates the minimum-spanning-tree of that delaunay triangulation,
with weights given by line length in points
5. Adds back a subset (default 10-15%) of edges from the delaunay
triangulation to the graph
6. Uses the resulting graph to draw corridors between the rooms, using a
random point on the near edge of each room to pick the points of the
corridors
Add a Door entity and an Open command, which necessitated supporting the
direction prompt. Currently nothing actually puts doors on the map,
which puts a slight damper on actually testing this out.
