move parallel-tactic to solver level

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>

src/solver/parallel_tactic.h

@@ -0,0 +1,27 @@
+/*++
+Copyright (c) 2017 Microsoft Corporation
+
+Module Name:
+
+    parallel_tactic.h
+
+Abstract:
+
+    Parallel tactic in the style of Treengeling.
+
+Author:
+
+    Nikolaj Bjorner (nbjorner) 2017-10-9
+
+Notes:
+   
+--*/
+#ifndef PARALLEL_TACTIC_H_
+#define PARALLEL_TACTIC_H_
+
+class tactic;
+class solver;
+
+tactic * mk_parallel_tactic(solver* s, params_ref const& p);
+
+#endif