added option --model-u-dt-enum for outputting uninterpreted sorts as datatype enumerations + minor update to array rewriter to improve output for this option, minor refactoring of representative selection for quantifier instantiation, initial draft of disequality propagation option --uf-ss-deq-prop, other refactoring of uf strong solver, fixed bug 496, improvement for fmf enumeration of finite built-in sorts