Magic's back, baby!

Work for #55.
Throw the bubble in the direction you face
Give magic a lifetime
Have magic affect enemies

Fixes #55.
Keymap stuff for magic
Play a sound when magic hurts the enemy
Limit possible castings with MP
Also draw HP meter as percentage
Regenerate MP based on magic stats
Have zap do something
Lead magic that goes down
Serialize magic stuff
Use the right item icon for lead
Merge pull request #102 from mccoyst/magic

Magic