snmpd:
	- rethink transports a little bit: make them loadable and make
	a private subtree for transports:
		OK. Table not writeable yet.

	There should be a transport table that is indexed by the transport name.
	This table can be used to load/unload transports at run time.
		OK. Table not writeable yet.

	Then there can be a port table that is indexed by transport name and
	port name. Plus a transport-specific table indexed by port name only.

	The transport table could contain a column of type OID that points
	to the transport-specific table.
