Merge pull request #28 from Aninimouse/master

2 Houses, 2 Gun Stores, and minor fix
Improve error message when Map::draw_tile can't find a glyph - try to tell us what Mapgen_spec it's from!
Mark lots of terrain with the container flag.  Meant to do this a while back; it permits solid terrain to have items.
Some fixes to maps.
Merge pull request #29 from Aninimouse/master

New House, Gun Store tweaks, Hedge terrain tile