Removed the Archer metaclass.

Archers and Slingers merged into Archer, under the Warrior metaclass
Archers now get both a bow and a sling at birth, along with both one point in bow and sling mastery


git-svn-id: http://svn.net-core.org/repos/t-engine4@4208 51575b47-30f0-44d4-a5cc-537603b46e54