Using an odd number prevents single index offsets in placement in
case of an even size

Also, modify the default window size to 3 instead of the previous
value of 4 (even number resulting in a potential offset).

Conflicts:
	tests/retrieve/test_simple_moment_calculations.py

…nd end indices

…re updated accordingly

…zation with Py-ART after 'determine_sweeps' is called

…mple_objects

Co-authored-by: Max Grover <mgroverwx@gmail.com>

Co-authored-by: Max Grover <mgroverwx@gmail.com>

Conflicts:
	pyart/util/radar_utils.py

This parameter scales the distance in the z-dimension when calculating
weights upon gridding. It is a semi-equivalent to the scaling factors in
the RoI class methods. Example for using this parameter would be setting
a 'zdist_factor' value of 0.0 combined with an h_factor=0.0 (if calling
DistBeamRoI) or z_factor=0.0 (if calling DistRoI), resulting in the
exclusion of the z dimension in gridding weighting, which could serve as
a potential solution for gridding a single PPI sweep from a single radar.
In that case, the distance in the weighting function effectively serves as
the distance of a given point from the PPI sweep's cone.

…map_gates_to_grid

In parts of the 'map_grid' method it was referred to as 'dist' whereas
in another as 'dist2' (parameter calculation lines differ in style but
identical in value), resulting in an unnecessary scalar allocation,
and a confusing nomenclature.

Co-authored-by: Max Grover <mgroverwx@gmail.com>