reverting portfolio hack
Merging Tim's pseudoboolean work from his fmcad14 branch.

Signed-off-by: Morgan Deters <mdeters@cs.nyu.edu>
Some news about API changes.
Add new --pb-rewrites options to QF_LIA run script for SMT-COMP.
fixing bv ackermanization cache bug
fix in sets rewriter
user/sat context issue in sets
sets: comment out an assertion too strong
disable failing test
disable another test, after recent merges taking too long
fixed unit tests failures
Merge pull request #31 from kbansal/sets

Sets
Some clean-up, post bv-merge.

Add abc to build id and fix static building.

Add abc to --show-config output and Configuration class API.

Add ability to select abc source path.

Fix arch_flags for abc.
--best now implies --with-glpk --with-abc
Fix an omission in bv sources.