Added an Item_manager class, and the global item_controller to reference it's only instance.

It is fully initialized as part of game.cpps initialization step, and doesn't do much for the moment aside from providing another way to access the same information already accessed through the itypes map. However, it lays the groundwork for additional changes.

To insure proper functionality, calls to itypes in wish.cpp now use the new item_controller.
Merge branch 'master' into add_item_manager
Bugfix for hot foods in containers not cooling down.  Fixes #336
Added the ability to ask the itemm_controller for a random id or itype from a group.
Fix traps overwriting each other.
Made the message when you attempt to close the curtains from outside more informative.
Added new IF_NO_UNLOAD flag, used to prevent a weapon from being unloaded. (Charge rifles, LAWs, etc).
Remove >< from possible inventory letters
Merge pull request #351 from Voker57/fixes

Remove >< from possible inventory letters since they make items inaccessible
Added M72-LAW. Placed it in the Soldier & Helicopter Mapextras, and the launcher spawnlist.
Merge branch 'master' of https://github.com/TheDarklingWolf/Cataclysm-DDA
My LAW goes FWOOSH! Added changes to changelog.
Merge branch 'master' of git://github.com/TheDarklingWolf/Cataclysm-DDA
Renamed silencer to suppressor.
Change code references for silencer to suppressor to match ingame name.
Actually changed all references of Silencer to Suppressor
Merge branch 'master' of git://github.com/TheDarklingWolf/Cataclysm-DDA
Merge remote-tracking branch 'dda/pr/347' into dda-master
Remove a ton of commented-out code.
Kill trailing whitespace\!