Renamed type synonyms in Golog.Interpreter.

We now have only two type synonyms, Conf and ConfIO, both with a payload
parameter.
Also renamed treeIO to treeNDIO.

Before, we had Conf, ConfND, ConfDT, ConfIO (which actually should have
been ConfNDIO) and ConfDTIO, only Conf of which had a payload parameter.
However, ConfND, ConfDT, ConfIO and ConfDTIO were only used once each:
in the treeND, treeDT, treeIO, treeDTIO functions.
Introducing a type synonym which is used only once seems mindless.

The sync function, however, had an ugly signature because it used the
general Conf type synonym and thus had to explicitly mention the SyncIO
payload parameter. Now the new SyncIO fits this job.

The new type synonyms also make searching easier. E.g., if someone wants
to check which functions to use to obtain something that can be handed
over to sync, she just needs to search for ConfIO as used in sync's
signature.