ho matcher draft

Draft implementation of higher-order matcher.
No specific tuning at this point.

src/test/CMakeLists.txt

@@ -58,6 +58,7 @@ add_executable(test-z3
   heap.cpp
   heap_trie.cpp
   hilbert_basis.cpp
+  ho_matcher.cpp
   horn_subsume_model_converter.cpp
   hwf.cpp
   inf_rational.cpp

src/test/main.cpp

@@ -270,4 +270,5 @@ int main(int argc, char ** argv) {
     TST(sls_test);
     TST(scoped_vector);
     TST(sls_seq_plugin);
+    TST(ho_matcher);
 }