z3/spec/plan.md

Your task is to implement the theory solver for strings that is described in the resources under reference.md

The theory solver should be implemented as a theory solver in src/smt. Call it theory_nseq.

Add a parameter setting to control whether using the default string solver theory_seq or theory_nseq or the empty string solver.

Utilities that can be made self-contained go in the directory ast/rewriter.

Start out by creating a plan for this implementation.