ac_atan2_cordic - range of angle

[smirre111]

The ac_atan2_cordic implementation calculates an angle in range [-M_PI, M_PI).
While this is nice and correct, in hardware it makes much more sense to scale the angle to be in the range of [-1, 1).

With that, the natural periodicity of the angle/phase is guaranteed and the number range is used with 100% efficiency.

A template parameter could allow scaling of the LUT and other impacted constants by M_PI.