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.
Merge branch 'next' into delay

Conflicts:
	src/canemulator.cpp
Fix test suite by adding timer mock.
Merge remote-tracking branch 'origin/delay' into 60-can-status
Fix timer delay on PIC32.
Add a function to timer.h for retreiving current system time on all platforms.

Currently implemented for PIC32.
Track whether or not the CAN bus is active.

Fixed #60.
Return proper type in test mock for timer.
Add a timer to calculate system time on LPC17xx.
Remove use of non-portable MAX - wasn't necessary here anyway.
Use CMSIS timer library for system clock on LPC17xx.
Use CMSIS/CDL library for delay timer, too.
Merge branch 'next' into 60-can-status
Store system clock as milliseconds, not microseconds.
Merge branch '60-can-status' into next
Allow baud rates greater than 115200 on PIC32.

Fixed #67