ENH: First attempts to walk in 3d space
ENH: First attempts to walk in 3d space

Contains two new elements:

volcoords_from_polar is a convenience function
to create 3D-Cartesian coordinates from 3D polar coordinates based on
georef.polar2latlonalt and georef.project

CartesianVolume is a class to interpolate 3-D polar volume data to
a regular 3D grid

wradlib/wradlib,heistermann/wradlib,heistermann/wradlib,kmuehlbauer/wradlib,kmuehlbauer/wradlib,wradlib/wradlib