correct conversion vtimage <-> numpy.ndarray

data/p58-t0_INT_down_interp_2x.inr

examples/image_visu.py

src/vt/tools.py

tst/test_apply_trsf.py

tst/test_blockmatching.py

tst/test_regionalext.py

tst/test_tools.py

tst/test_vt_image.py

tst/test_watershed.py

wrp/python/vtImageBridgePython.cpp