Pr issue13

[rneswold]

At the moment, I'm working on phase 1 of the issue which adds some type-safety to the driver's API. Drivers need to report values and receive values (for settable devices.) This requires changes in 3 types:

• The ReportReading closure now takes a type parameter. When registering a device, its type is also declared. No longer can one accidentally save a String for a bool device.
• When registering, the previous value (if any) of the device is returned. This value needs to be converted to the device's type (instead of just being a device::Value.
• Incoming settings need to convert device::Value types to the device's declared type. If it can't, the API should automatically send a TypeError back to the client.

At this point, I've pushed commits which support the first two requirements. I'm still working on the third.

This pull request will close out #13.

[rneswold]

At this point, phase 1 is complete. I want to add unit tests, however, before we merge this into main.

[rneswold]

Now to start phase 2. 😬