Add functions lo_server_new_from_url() and lo_server_thread_new_from_url().

Allow to specify lo_server parameters in a single URL-style string,
just like for lo_address.  Adds a couple of sprintf calls in
lo_url_get_port() to handle the case where no host is provided, since
server specification only needs a port. Still may need some kind of
syntax extension to allow specifying multicast interface selection.
Allow oscsend and oscdump to specify port and dest address via URL string.

Note that this allows using TCP with these tools, although some
features are still missing without certain extensions like specifying
the network interface or selecting the SLIP packetizing protocol.
Add release notes for 0.27.
Update the ChangeLog based on git commit log.