GeomNorm bindings cannot be used with color images

In the bindings of GeomNorm, both gray and color images are allowed: https://gitlab.idiap.ch/bob/bob.ip.base/blob/master/bob/ip/base/geom_norm.cpp#L315

However, only the gray level version is called: https://gitlab.idiap.ch/bob/bob.ip.base/blob/master/bob/ip/base/geom_norm.cpp#L256

This results in an unreadable error message, when I try to use a color image:

>>> import bob.ip.base, numpy
>>> img = numpy.ndarray((3,128,128), numpy.uint8)
>>> res = numpy.ndarray((3,64,64), numpy.float64)
>>> geom = bob.ip.base.GeomNorm(0., 1., (128,128), (64,64))
>>> geom.process(img, res, (64,64))
RuntimeError: bob.ip.base.GeomNorm - cannot process image: C++ exception caught: 'array dimensions do not match 0 != 128'

The bindings need to be fixed.