MAINT: skel3d: minor sty/perf fixes
MAINT: skel3d: minor sty/perf fixes

* remove commented out code
* statically type tuple of ints

rjeli/scikit-image,pratapvardhan/scikit-image,paalge/scikit-image,ofgulban/scikit-image,paalge/scikit-image,paalge/scikit-image,pratapvardhan/scikit-image,Hiyorimi/scikit-image,ofgulban/scikit-image,ofgulban/scikit-image,vighneshbirodkar/scikit-image,rjeli/scikit-image,Hiyorimi/scikit-image,rjeli/scikit-image,ajaybhat/scikit-image,vighneshbirodkar/scikit-image,vighneshbirodkar/scikit-image,ajaybhat/scikit-image