corrections for tests

src/vt/apply_trsf.py

src/vt/apply_trsf_to_points.py

src/vt/blockmatching.py

src/vt/cellfilter.py

src/vt/compose_trsf.py

src/vt/connexe.py

src/vt/create_trsf.py

src/vt/inv_trsf.py

src/vt/linear_filter.py

src/vt/mean_images.py

src/vt/morpho.py

src/vt/pointmatching.py

src/vt/regionalext.py

src/vt/tools.py

src/vt/watershed.py

tst/test_apply_trsf.py

tst/test_blockmatching.py

tst/test_compose_trsf.py

tst/test_create_trsf.py

tst/test_inv_trsf.py