hdfarchive + gf : two corrections

- hdfarchive : transform the key to string with str
  because they can be unicode and C wrapper does not convert python unicode strings.
- gf : Correct the scheme for BlockGf : not very clean, to be improved ?

pytriqs/archive/hdf_archive.py

@@ -253,7 +253,7 @@ class HDFArchiveGroup (HDFArchiveGroupBasicLayer) :
             except KeyError : 
                 raise RuntimeError, "I can not find the class %s to reconstruct the object !"%r_class_name
             if r_readfun :
-                res = r_readfun(self._group,key) 
+                res = r_readfun(self._group,str(key)) # str transforms unicode string to regular python string
             elif "__factory_from_dict__" in dir(r_class) : 
                 f = lambda K : SUB.__getitem1__(K,reconstruct_python_object) if SUB.is_group(K) else SUB._read(K)
                 values = dict( (self._key_decipher(K),f(K)) for K in SUB )

triqs/gfs/gf.hpp

@@ -320,7 +320,8 @@ namespace gfs {
   //----------------------------- HDF5 -----------------------------
 
   friend std::string get_triqs_hdf5_data_scheme(gf_impl const &g) {
-   return "Gf" + gfs_implementation::h5_name<Variable, Target, Opt>::invoke();
+   auto s = gfs_implementation::h5_name<Variable, Target, Opt>::invoke();
+   return (s == "BlockGf" ? s : "Gf" + s);
   }
 
   friend struct gfs_implementation::h5_rw<Variable, Target, Opt>;