first introduction of timer interrupt for servo control
clean up and refactor servo movement logic
throw out some unused methods
using scanning angles, setting max distance
rate limit sonar pings
rate limit sonar pings
 - Drive action runs continuously, even through a range scan (this is good)
 - turn if new turning angle set, clear turning angle after
 - normal and high-speed ping rates
 - start a scan immediately after backing up
 - seperate methods for straight-ahead range and not-straight-ahead range
use trigonometric function to favour angles closest to straight ahead