Added first round of work on lantern files.

The lantern is based on the gravity gun, so it has some uneeded code for now,
yet this contains the first gameplay basics of it.
Added the lantern files in the build list.
Added lantern oil as ammunition type.

This will allow to get the ammunition type for the lantern and to add it to maps
(temporarily can change the other ammunition boxes in item_ammo to give the user "oil")
Changed default assignment of items to player to give him only the lantern.
Changed the name to Haunt ;)