Final preparations for arithmetic for building with libc++.
Another fix for the CASC stuff.
Documentation clean-ups.
Code cleanup.
Merge pull request #33 from mdeters/arith-proposal

Final preparations for arithmetic for building with libc++.
New translator features: expand define-funs and combine assertions.
No more dependence on libstdc++ or PBDS stuff: remove build stuff that supported it.
More minor code cleanup.
Better approach to forcing string logics to contain UFLIA also.
Automatically make SMT options from command-line option names, warn when not possible.
Fix query/checksat dumping.