Add error and status code block types

[AngusJull]

Added error and status block types. Both have a measurement time to denote when the error or status update occurs, though I've written the status block to allow for re-transmission of the same status message as an update.

Status blocks

• Allow for state, event, and a nominal operation message. The nominal operation message could be left out, but it might be useful to have for startup or if there's error handling we do.

Error blocks

• Included fields for the originating process (in case we want to track down which thread caused an error, or in case we can attribute errors to specific pieces of hardware). For now, I've left the specific values as implementation defined besides 0x00, because I don't want to lock us into one design for the system or make our radio format outdated if we add another thread. We can just debug this after the flight or look up the values we chose on-demand.
• Included a field for severity. Chose some okay default options, leaving 3 left for future use. We probably don't need all of these, but I didn't know what to do with extra bits anyways. Let me know if they'd be better reserved.
• Left the definitions of error codes as implementation defined. I think we'll have a lot of these, and they can have very specific meanings if we just leave them to be defined by telemetry. I'm planning on having every error case have its own code so its easy to know exactly where an error came from.

[linguini1]

I could maybe see an error packet with the process ID, but I don't really understand the utility of anything else. What are we going to do if we receive an error block that says "INFO: Process 2"? That doesn't really tell us anything. Anything below a critical error probably should not be transmitted in flight.