A slice solver option for interactive use case

A slice solver prunes the set of active assertions based on symbol occurrences in a goal that is tracked as a @query.
Ground assertions that have symbols intersecting with the query are included in the solver state, and quantifiers that with patterns that intersect with the slice are included. The slice is the fixedpoint of including symbols from all included assertions.
Enable the functionality for command-line use by setting solver.slice=true

Author: NikolajBjorner

src/params/solver_params.pyg

@@ -8,6 +8,7 @@ def_module_params('solver',
                           ('lemmas2console', BOOL, False, 'print lemmas during search'),
                           ('instantiations2console', BOOL, False, 'print quantifier instantiations to the console'),
                           ('axioms2files', BOOL, False, 'print negated theory axioms to separate files during search'),
+                          ('slice', BOOL, False, 'use slice solver that filters assertions to use symbols occuring in @query formulas'),
                           ('proof.log', SYMBOL, '', 'log clause proof trail into a file'),
                           ('proof.check', BOOL, True, 'check proof logs'),
                           ('proof.check_rup', BOOL, True, 'check proof RUP inference in proof logs'),

src/solver/CMakeLists.txt

@@ -6,6 +6,7 @@ z3_add_component(solver
     mus.cpp
     parallel_tactical.cpp
     simplifier_solver.cpp
+    slice_solver.cpp
     smt_logics.cpp
     solver.cpp
     solver_na2as.cpp