TODO-constraints.txt

* change ||, &&, if-then etc interpretation so we can add them to a solver (Z3)
* allow variables to be shared between solvers
* allow constraintvariables specialization (e.g. when they're used in a constructor and are still nil, but should be a Fixnum)
* extend libarraysolver to work for non-numeric arrays
* make solvers assign new values eagerly, to trigger downstream solvers correctly