function_on_ definitions simplified

[Peter Dobcsanyi]

The schema definitions for functions have been simplified.
<map_entry> was removed and <map> took over its role.

Here is how the new definitions look like:

   function_on... element function_on_... {
      # attributes
      ...
      map +
   }

   map = element map {
      ( preimage | preimage_cardinality | blank )
      ,
      element image { n | d | not_applicable }
   }


The RNC version was bumped to 1.0rc2.

--             ,
    Peter Dobcsanyi