minor changes to make safer

eliminated multiple accesses to Yocto at same time (it didn't like
that!). switched autosmoker back to GPIO.RPi from RPIO in attempt to
isolate intermittent but recurring bugs.
replaced a couple of missed calls

replaced some calls that I had intended to replaced, but missed.
Minor tweaks

Eliminated jitter of servo, increased reliability of system by
decreasing duration of DMA access, amongst other things. Servo reader
uses tolerance for deciding whether or not to move servo.
Merge pull request #17 from mattstarr/makethreadsafer

Makethreadsafer