Mutexed things, renamed cameras, added buzzer.

Made several significant changes to the base system.  Firstly, the
sensor daemons now have mutexs (except for running, which I only just
realised).  The camera daemons have been renamed such that the plain
camera class does not detect red objects; that's left to the
variations.  Also, I've added Merrick's connected component search as
camera_var4.  Current versions of my track_red_object and
face_red_object probably won't compile anymore.  I've also added a
buzzer class that kinda works (frequency is deceptive, but you'll know
what I mean when you test it) and there's a rather useless modePin
wrapper now.  Finally, I've also calibrated the pwm signals in gpio to
the gimbal channel.
More of the last commit.