Warn if the CAN bus mapping is missing speed.
Document that only 0x101 and 0x102 are accepted as bus addresses.
Remove misleading docs about using output of xml_to_json for code generation.
Remove outdated default arguments to xml_to_json.
Update to 2.1.2.
Add a timer interface for adding delay if we need it.
Slow down emulator speed by sending every nth time through the loop.

Want to still process USB, just don't queue too much. It's not like any vehicile
we would see and it's making debugging with the emulator difficult.
Draft of possible LED light API and partial implementation for LPC1768.
Merge commit '136731c'

Conflicts:
	docs/definitions/mappings.rst
Bump to v2.1.3.
Merge remote-tracking branch 'origin/master' into next

Conflicts:
	CHANGELOG.mkd
	README.rst
	docs/conf.py
	docs/index.rst
	src/main.cpp
Merge branch 'next' into lights
Implement basic LED control on LPC1768/69, without dimming.
Merge branch 'delay' into lights

Conflicts:
	src/canemulator.cpp
Add some test LED flashing when the main loop spins.
Increase PWM frequency to avoid blocking too long.
Flash a blue LED when an output message is queued.
Minimize time blocking for LED.
Only delay on LPC if the duration is > 0, just to be safe.
Make sure _cygwin_error is defined before it is used.