Add debug variable support

Signed-off-by: Morten Hustveit <morten.hustveit@gmail.com>
controller.cc: Calculate total odometry and add reset key

This was used to determine that there are exactly 60 Hall effect transitions
per motor revolution in the curvy motors.  The gear ratio of the motor is
73/17.

Signed-off-by: Morten Hustveit <morten.hustveit@gmail.com>
Added /controller to .gitignore

Signed-off-by: Morten Hustveit <morten.hustveit@gmail.com>
controller.cc: Added speed measurements

Signed-off-by: Morten Hustveit <morten.hustveit@gmail.com>