Add meta information to a Symbol.
                
        Parameters
        ----------
        metadict 
            Attributes are passed as keywords, with their
            associated values as strings.  For meta attributes with spaces,
            use an unpacked dict.

def add_meta(self, **metadict):
        """Add meta information to a Symbol.
                
        Parameters
        ----------
        metadict 
            Attributes are passed as keywords, with their
            associated values as strings.  For meta attributes with spaces,
            use an unpacked dict.
                    
        """
        
        objs = object_session(self)
        
        for attr,val in metadict.iteritems():
            newmeta = SymbolMeta(self, attr, val)
            self.meta.append(newmeta)
            
        objs.commit()