Since the Type Specific user facing entities did not actually wrap the
DDS entities, but connected to them through port signals, a more
semantically correct name would be "interface", since they are the user
facing interface of the DDS entities.
Until now the rtps_builtin_endpoint was using the last parsed Locator as
the Locator of choice.
The rtps_builtin_endpoint was extended with a PREFER_MULTICAST boolean
generic that allows to influence which locators are used.
Test1 of rtps_builtin_endpoint was split in two, to test both settings
of the generic.
