Report all probes

[speshak]

Fixes #45

[CLAassistant]

All committers have signed the CLA.

[speshak]

I'm opening this now as more of an RFC before I go further. There are a couple outstanding issues that at least need discussed:

• The "keywords" I chose for extending the PiLink protocol. I used T and o, but there might be better options.
• Being more defensive in how the custom names are stored. If you were being malicious, you could overwrite some of the other system data by claiming a device address of /mdns.txt
• Is there a reason why parseJsonToken eats spaces? This means that no probe name can have a space. That could be a reasonable trade off, especially if other code paths depend on that behavior, but it was a bit surprising when I was testing.

[speshak]

I've answered my own question about parseJsonToken. That function is used for both JSON keys and values, and spaces (and the other skipped chars) aren't valid in a key.

[lbussy]

[speshak]

I fixed the issue with possibly squashing other SPIFFS content, and added another PiLink command (p) for dumping the list of configured device names. I think this is ready for review.