Use a struct packet instead of an array

[pdbogen]

There are flaws in the library's handling of packet transmission and reception that result in buffer overflows and memory corruption. I'm fairly certain these are specifically due to the use of short uint8_t arrays to send and receive packets; where the arrays are based on the sent packet payload without regard to the length of the respond payload. There are even compiler warnings about this.

My fix is to utilize a single struct that encompasses all the fields of the packet, and names them. I'm currently using a fixed body of 64 bytes, which may be excessive; but I don't know the protocol well enough to know what the largest actual packet size would be.

This works for my use case, seems reliable, and does not exhibit the system-breaking behavior of the existing library's overflows.

• Scope: All command functions.
• Limitations: None known.
• Examples: I'm using the main functionality of the device in my own code but I haven't tested with the examples. I'll try this out tomorrow.

[ladyada]

yay rad! hand-merged