Rewrote how hall traps work.

* Issue #70
* projectile traps now unlootable. Issue #165
* Portcullises are now functional Issue #16
* Removed arrow* keys from config
* Removed portcullis* keys from config.
* Removed piston keys from config.
* Added [hall traps] section.
* Removed [dispensers] and added [projectile traps]
* Removed portcullises.py
* Portcullises are now a type of hall trap.
* addtileentity() helper in dungeon class.
* get_tile_entity_tags() helper in utils.