Refactoring of model engine to separate individual implementations of model builder.  Begin work on interval models for integers.  Other minor cleanup.
Re-enable predicate subtyping, reversing commit 8f9f549 (needed for Kind integration)
fix for lambdas in relation to subtypes
fixup for miplib trick (related to lambda fix for subtypes)
subrange-related fix
new --tear-down-incremental mode
new --force-logic option that overrides what the input says
more ITE rewrites
some of the minisat markers/assumption framework
Revert "subrange-related fix"

This reverts commit 771943753d540defa4e708667f70fee131462367.
fix bug in ITE rewrites