If the command response is not a known value, assume it is an integer.

This means that some commands which return a value now work, e.g.:
$ onkyo main.master-volume=query
<eISCP(TX-NR414) 192.168.55.5:60128>: MVLQSTN
('master-volume', 15)

Some other commands continue to fail, such as main.tone-front=query