fixed Assignable in concept_checks.hpp and changed the name of

concept_skeletons to concept_archetypes. Made lots of additions/changed
in concept_archetypes.


[SVN r8061]

libs/concept_check

@@ -1 +1 @@
-Subproject commit f06d9504c7747e59f5e3b17a4d3cd2bc4e43a655
+Subproject commit 72f2233aa3ae16b3fe92679a79257ae98f3a8dab