added javadoc for why the Colors enum exists
changed CompoundFrame to use a pre-sorted Collection of modifiers, rather than a SortedMap, and added FrameType.minus(FrameModifier) to complement plus.
added COLORLESS to the Colors enum and renamed to ManaColors
added test cases for CardSet
wrote a cost parser that will turn a cost string into a list of CostType values
removed pluralization
added sorting of the cost, according to cost ordering rules
added color associations to cost types
added some deduction methods to Card