Move pairing into a module & split logic up into sub-modules. Clean up pairing code.

[jkaczman]

In preparation for adding BLE logic, worked on making the pairing code easier to work with and more modular.

Split some functions up into multiple, fixed some areas that weren't propagating errors, simplified some unnecessary complex logic.

[arrdalan]

Thanks.

It's not very clear to me how the code is split between the new files, especially general.rs and io.rs. For example, I see some TcpStream-related code in general.rs. Should that go under io.rs? It might be helpful to add some comments to these files explaining what each is for.

[jkaczman]

Thanks.

It's not very clear to me how the code is split between the new files, especially general.rs and io.rs. For example, I see some TcpStream-related code in general.rs. Should that go under io.rs? It might be helpful to add some comments to these files explaining what each is for.

Thanks for the review! I added some comments in mod.rs explaining the split of responsibilities. How does that look?

[arrdalan]

Looks good. Thanks!