API breakage:

rename _constains into _contain_p
to be more uniform with other predicate functions,
and to use infinitive form for the method.

m-algo.h

@@ -103,7 +103,7 @@
   }                                                                     \
                                                                         \
   static inline bool                                                    \
-  M_C(name, _contains) (container_t l, type_t const data)               \
+  M_C(name, _contain_p) (container_t l, type_t const data)              \
   {                                                                     \
     it_t it;                                                            \
     M_C(name,_find)(it, l, data);                                       \