Add support for value lists to mp_assign, mp_clear. Refs #53.

test/Jamfile

@@ -29,6 +29,10 @@ run mp_size.cpp ;
 run mp_size_2.cpp ;
 run mp_empty.cpp ;
 run mp_empty_2.cpp ;
+run mp_assign.cpp ;
+run mp_assign_2.cpp ;
+run mp_clear.cpp ;
+run mp_clear_2.cpp ;
 run mp_front.cpp ;
 run mp_pop_front.cpp ;
 run mp_second.cpp ;
@@ -54,8 +58,6 @@ run mp_list_v.cpp ;
 run mp_rename_v.cpp ;
 
 # algorithm
-run mp_assign.cpp ;
-run mp_clear.cpp ;
 run mp_transform.cpp ;
 run mp_transform_q.cpp ;
 run mp_transform_sf.cpp ;