Add sylvan_seq.xpp

CMakeLists.txt

@@ -30,8 +30,8 @@ add_library(sylvan
     sylvan_mtbdd_int.h
     sylvan_obj.hpp
     sylvan_obj.cpp
-    sylvan_seq.hpp
-    sylvan_seq.cpp
+    sylvan_seq.h
+    sylvan_seq.c
     tls.h
 )