Allow diagnostic message responses.
Merge branch 'next' into diagnostics
Update code generator to match VI - using CanMessage in signals.cpp.
Decode protobuf diagnositc message responses.
Support diagnostic messages in config files.
Set bus and active status on mapped diagnostic messages.
Set active status on mapped commands.
Grab proper diagnostic 'handler' attribute from configs.
Add a draft of a new diagnostics command line tool.
Note a question about the bRequest type for control transfer.
Remove deprecated reset command for VIs.
Add factor/offset attributes to diagnostic messages in firmware config.
Use new diagnostic message functions in generated code.
Merge branch 'next' into diagnostics
Allow frequencies less than 1Hz for diagnostic requests.
Merge branch 'diagnostics' into diag-cc

Conflicts:
	openxc/controllers/base.py
	openxc/controllers/usb.py
	openxc/sources/usb.py
Fix grammatical error in error output.
Hack in some sleep before diag requests to fix control command.
Convert mode, pid and frequency from command line strings to ints.
When sending a diag request, put frequency in request object not parent.