Rename strided_dim to fixed_sym_dim (symbolic fixed dim)

Also follow through fixes throughout
Restore the arrmeta size to fixed_sym_dim_type, some view enhancements

It might be useful to allow the symbolic fixed dim to be used
in some concrete cases across interface boundaries. The
neighborhood code is currently doing this, but maybe it could
change to concrete fixed dims as well.
Merge pull request #138 from mwiebe/rename_strided

Rename strided_dim to fixed_sym_dim (symbolic fixed dim)