Change Catalsyt _parse_attrs so that when sub attr handlers:

Change Catalsyt _parse_attrs so that when sub attr handlers:
1) Can return multiple pairs of new attributes
2) Get their returned attributes passed through the correct attribute handler.
e.g sub _parse_Whatever_attr { return Chained => 'foo', PathPart => 'bar' }
Will now work because both new attributes are respected, and the Chained attribute is passed
to _parse_Chained_attr and fixedup correctly by that.