Sony SRS-X88 support

[seanb-uk]

Just to let you know, this mostly works with a Sony SRS-X88.

I had to change the API version for get_inputs (mine is 1.1, not 1.2). The SRS-X88 also has some problems with sources - when you select the network source it shows the streaming service in use rather than the selected source.

I've written up that issue on another project that's also working on the Sony speaker support: rytilahti/python-songpal#5

If you're still working on this project it might be worth comparing.