added doc to PaintTool
added doc to PaintTool

some doctest on showa

more doctest skip

deleted unwanted spaces

reference to paint object skipped

unwanted _

typo in #doctest

fixing coverall problem

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