bug fixes for the PyPi installation

MANIFEST.in

qim3d/gui/iso3d.py

qim3d/gui/local_thickness.py

qim3d/img_examples/NT_10x200x100.tif

qim3d/img_examples/NT_128x128x128.tif

qim3d/img_examples/blobs_256x256.tif

qim3d/img_examples/blobs_256x256x256.tif

qim3d/img_examples/bone_128x128x128.tif

qim3d/img_examples/cement_128x128x128.tif

qim3d/img_examples/fly_150x256x256.tif

qim3d/img_examples/shell_225x128x128.tif

setup.py