using a consistent naming convention for naming tactic subfolders

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>

src/tactic/core/der_tactic.h

@@ -0,0 +1,25 @@
+/*++
+Copyright (c) 2012 Microsoft Corporation
+
+Module Name:
+
+    der_tactic.h
+
+Abstract:
+
+    DER tactic
+
+Author:
+
+    Leonardo de Moura (leonardo) 2012-10-20
+
+--*/
+#ifndef _DER_TACTIC_H_
+#define _DER_TACTIC_H_
+
+class ast_manager;
+class tactic;
+
+tactic * mk_der_tactic(ast_manager & m);
+
+#endif /* _DER_TACTIC_H_ */