Added CondensedPatternMatrix.
Improved code for removing all-gap characters to make it much faster.
fixed bug in CategoricalData such that setToInapplicable actually set
the data to inapplicable.
Reduced the frequency of progress reporting when saving a matrix.
Merge branch 'master' of https://github.com/wmaddisn/MesquiteCore
Clean up of CondensedPatternMatrix code