The current codebase has a lot of different things interleaved in often unpredictable ways; for example, stuff that controls how data is printed to the console being in the same basic areas of the code as sending and receiving data, and both of those together with code that controls things like managing client connections.

We should more clearly separate these things for a couple reasons:

• those using the library to write larger applications that do things very differently from a CLI shouldn't be subject to how data is printed to a console, but should be able to reuse convenience functions around things like administration, sending different sorts of data formatted correctly, etc.
• those writing separate special-purpose CLI scripts can benefit from some parts of our CLI code (for example, setting up an appropriate client from host/port/BLE options, or waiting for acknowledgements) but not need/want everything we do right now.
• it's a lot easier to maintain something where it's easier to find each bit of code!

I think this might get broken up a few different ways and I'm not sure exactly what I think should be done here, but I wanted to get the issue out here to discuss things.

Closely related to #569 since separating the concern of presentation from that of acquiring data is key to that.

Previously: #566