Saturation problem in arm_absmax_no_idx_q(7|15|31)
Difference of behavior for absmax_q(7|15|31) between reference and code:
reference is first max found. Code was last max found.
arm_cmplx_mag_q15 reworked to be more accurate but less efficient.
New function arm_cmplx_mag_fast_q15 introduced to retain previous
(less accurate) but faster behavior.
Improvement to Python wrapper to support the new functions.