A different meter list response with named meter topics

[stephenhouser]

Currently the meter list command returns an object that is parsed from the radio response. To assist in knowing what the meter name is for the named meter system an additional field topic is injected into the meter objects. While this helps, it might be more useful to have these meters indexed by these topics rather than their dynamic meter number.

The current result of a meter list is:

{
...
"15": { src: "TX-", num: "8", nam: "GAIN", ..., topic: "TX-/8/GAIN" }
...
}

This idea would either change this or add a new format response that would be:

{
...
"TX-/8/GAIN": { src: "TX-", num: "8", nam: "GAIN", ... }
...
}

One issue is where or how should the original meter number be reflected. Should it be a field in the meter list, perhaps meter_number