BAMPFA-79: Add support for early/mid/late year.
BAMPFA-79: Add support for millenia.
BAMPFA-79: Add support for quarter centuries. Also refactor deferred date classes.
BAMPFA-79: Add support for half centuries.
BAMPFA-79: DeferredDate refactoring.
BAMPFA-79: DeferredDate refactoring. Move DeferredDate classes out of antlr package.
BAMPFA-79: Add support for partial centuries.
BAMPFA-79: Add support for partial decades.
BAMPFA-79: Allow any singleInterval to be part of a hyphenatedRange.
BAMPFA-79: Add support for nth-nth century ranges.
BAMPFA-79: Add javadoc comments.
BAMPFA-79: Some work on before/after, mostly still commented out.
BAMPFA-79: Add README.txt.
BAMPFA-79: Some minor refactoring and comment editing.
BAMPFA-79: Implement scalar date computation. Also some refactoring.
BAMPFA-79: Add support for . following a display date, and following mid.