[ODE] AMotor small changes

[Russ Smith]

> what do you mean by saying "not API backwards compatible"?
> it's "Set" not "Get" that allows the outside -PI..PI in this addition
> from what I understand

the implementation did the angle change in the 
amotorComputeGlobalAxes() function, which would have affected not only
the get() call but also the interpretation of joint limits. somebody
somewhere might be relying on the existing behavior...

russ.

-- 
Russell Smith
http://www.q12.org