Updated the charts to use fewer images.

Using fewer images to show the charts with greater precision.  This way
if we want to change the chart images we wont need to update 100s of
images.
Merge pull request #9 from JayUnt/master

This commit enables auto-filling of images based on %

Example: If the keg is 68% full, the bottom 68% of the "full keg" image will display, with the remaining 32% of the "empty keg" image above (behind) it.

Previously, this functionality required separate rendered images. This is, for 100-points of control, there had to be 101 generated images.

This update will drastically shorten artwork update time.