Minor fix for explanations for co-datatypes.  Bug fix for explanations in FMF for quantifiers over arrays.
run_regression using valgrind by setting VALGRIND=1
initialization in model_engine
add delayed length lemmas
merging...
patch for regular expression intersection caching
fix for regexp union rewriting
bug fix for pierre 0717
Minor bug fix for exhaustive instantiation in model_engine.
New module for generating candidate equality conjectures used in inductive proofs.  Filtering currently includes: LHS generalizes a term from an active conjecture, terms must be canonical, conjecture must be confirmed by a ground witness, and cannot be falsified by a ground witness.  Refactoring of term database.  QcfEngine now uses central data structure for term indexing.  Add two options for quantifier instantiation : trigger selection mode --trigger-sel=mode, and --inst-no-entail which blocks all quantifier instantiations that are currently entailed (using an incomplete check).
Minor cleanup from previous commit.  Better organization for how quantifiers modules check (introduce QuantifiersEngine::QEffort).