bump new 0.0.0rc6

scan_ and contour_data wrapper add parameter pop/take
add basic contour
modify scan_stat_factory to account for alpha parameter
add marker option to scan

modified:   buildPackageAndDocs.sh
new file:   dist/pytom3d-0.0.0rc6-py3-none-any.whl
new file:   dist/pytom3d-0.0.0rc6.tar.gz
modified:   docs/conf.py
modified:   setup.py
modified:   src/pytom3d/scan.py
modified:   src/pytom3d/util.py
modified:   src/pytom3d/viewer.py