Catalog: add an 'implementation' param
Catalog: add an 'implementation' param

Add an 'implementation' parameter to some Get*String so we can temporarily
override the Catalog.Implementation.

Note: don't refactor this code to use parameters with defalt values, the
possibility of a null-valued Catalog breaks the AssemblyParser.

dsuess/vernacular,benoitjadinon/vernacular,gabornemeth/vernacular,benoitjadinon/vernacular,gabornemeth/vernacular,mightea/vernacular,dsuess/vernacular,rdio/vernacular,StephaneDelcroix/vernacular,StephaneDelcroix/vernacular,rdio/vernacular,mightea/vernacular