HA: configurable IA, Multicast group and port

[farmio]

I'm still not happy with having to set local_ip manually for routing connections, but I haven't found a way to configure it so that

knx:
  routing:
  expose:
    ....

or similar would be possible.

Should we change the configuration to something like that:

knx:
  connection_type: routing # or "tunneling"
  local_ip: 123 # optional - would fit for routing and tunnelling
# or
knx:
  connection_type: tunneling
  tunneling:
    host: 10.1.1.1
    port: 1234
# or
knx:
  connection_type: tunneling
  tunneling_host: 10.1.1.1
  tunneling_port: 1234

?

[coveralls]

Coverage remained the same at 92.136% when pulling 65ff504 on farmio:HA-connection-parameters into b59a8b8 on XKNX:master.

[marvin-w]

Changes look good. I like the last option most.

knx:
  connection_type: tunneling
  tunneling_host: 10.1.1.1
  tunneling_port: 1234

One thing:

In the tunneling connection schema you could as well define a default port:

gateway_port = self.config[DOMAIN][CONF_XKNX_TUNNELING].get(CONF_PORT)
        local_ip = self.config[DOMAIN][CONF_XKNX_TUNNELING].get(
            ConnectionSchema.CONF_XKNX_LOCAL_IP
        )
        if gateway_port is None:
            gateway_port = DEFAULT_MCAST_PORT

Just so that it's nice and tidy.

[marvin-w]

Looks good now, thanks! I'd suggest opening another PR for changing the connection params.