1. Scan message areas based on those listed in the areas.bbs, not those listed
in the msgs.cnf file (e.g. configured with SCFG->Message Areas). This allows
the same message base to be scanned more than one for a different set of
uplinks (i.e. gating).
2. Store the message base export pointer (in the data/subs/code.ini file) with
the echotag as part of the key-name. This allows the different upstream
networks to have different export pointers (though after a complete
scan the export pointers should be the same for each msg base).

Increment the version number to 2.20.