move PlexGDM under XMLConverter

- clean PlexConnect from PlexGDM
- XMLConverter is sole user and therefore responsible for GDM
- if PMS was not found and PlexConnect is entered, redo GDM and
discover server
- broke "XMLtemplate" selector into two parts: PlexConnectCmd vs.
ViewGroup dependant.
- suppress requesting PMS XML for settings toggle - should speed up
reaction.