o.c.numjy: Allow array(existing array); Remove min(a), max(a)

Compatible with numpy: Build-in min(a)/max(a) will work via
a.__iter__(), and a.min(), a.max() can be used as before for faster
execution.
o.c.numjy: Support 'import numjy as np' for CPython

.. falling back to C numpy
o.c.numjy: Implement ndarray.__abs__ instead of abs()

.. to be compatible with numpy
o.c.scan: Add gaussian.py, filter.py
Merge remote-tracking branch 'origin/3.2.x' into 3.2.x