- allow communication to elm327 device via a serialport
- allow creation of elm327 device without requiring unwrap()
- added some extra documentation
- expose reset() functionality of device
- serial_comm and ftdi_comm abstractions added
Also restructure the code to implement get_dtcs and get_dtc_info by
implementing GetObd2Values on the data types they return. This brings
them in line with every other getter function besides get_vin.
- Required new function obd_mode_command for commands without PIDs
- Required new reading function for single line responses
- Multiple devices can respond to get_dtcs, so the responses are now
vectors of the previous type - vectors of u8
