mercutio 0.9.4

Release of version 0.9.4
Docs: added documentation for Player.distribute()
Tests: added tests for success/failure conditions of distribute()
Added: code to permit Player.distribute() when no dimension argument is passed
Added: Player.distribute() method to distribute proficiencies IAW PHB, pg. 125
Docs: added some potential usage notes for 0.10.0
Docs: updated index
Added: proficiencies for backgrounds
Fixed: tests by moving test_customize_overwrite() to the end
Fixed: problems with reused, non-class keywords (player_class, background, etc) persisting across methods