[retdmacr] Retroactively defining a macro

Do some editing.  Do some more editing.  Call "End Macro Recording".  Repeatedly hit undo, or redo if you go back too far, until you get to the start of the edit operation.  Call "Begin Macro Recording".  All your undos are redone. 

Call "Push Macro And Begin Recording".  Do a movement, probably search, for the next location you want to invoke the pushed macro.  Call "Pop Macro and End Recording".