Merge pull request #24 from Jbtyson/Units

Units
Fixed Rotation. Removed some fields and functions.

Fixed rotation so that the rotation is done on the center of the image
and not the top left corner. Also removed unnecessary fields and
functions from the buildings, towncenter, barracks, and connector
classes.
Added some clearer icons for units.

Hoplite, Infantry, and Villagers all have unique icons.
Merged Master with Buildings.
add building functions