detail/concepts.hpp: added read only vector concept

storage_sparse.hpp: removed wrong structure check, added check for empty sequence to erase(it1, it2)


[SVN r51666]

libs/numeric/ublas

@@ -1 +1 @@
-Subproject commit c65fccf2d7e39dca268b2219c91a7bcafea2c61a
+Subproject commit 399e9eee1aba1ae9d961b054d7202f74a65a5f90