renamed CardSetImporter to XmlCardSetImporter to make room for the Markdown format
created CardSetReader and retrofitted XmlCardSetReader to implement it
created CardSetWriter interface as the inverse of CardSetReader to eventually be implemented to spit out XML descriptors
added getCardsInSet to CardSet
moved and morphed to the new APIs
added check for CardSet.key
moved StringUtils and it's test from the old src root to the utils module
added a getCost variant that takes a Collection of symbol Strings, in addition to the single (aggregate) String one.
moved a bunch of the low-level parsing stuff out of descriptor.TextParser and into util.StringUtils so it can be reused across modules
reimplemented parseTextAndSymbols w/ an inner class instead of a bunch of closures
fixed to return null when parsing text if there is no text, rather than an empty list
added an overload of parseTextAndSymbols that accepts an already-split list of paragraphs
resurrected support for Markdown-based descriptors atop the new data model.  The format remains unchanged excepting that:
 * power/toughness for creatures is supplied as the last line of the body, instead of as a suffix to the type line
 * braces are no longer supported for custom emphasis
 * <em> can be used for custom emphasis
 * <br /> (which must be self-closed) can be used for line breaks
Merge branch 'pre-delete-src'

Conflicts:
	theme/src/test/groovy/com/barneyb/magic/creator/theme/DynamicThemeTest.groovy