Make trailing whitespace less distracting and optional
Make trailing whitespace less distracting and optional

By using font-lock-comment-face, it's less distracting than the default
bright red, since comment face is designed to be subtle.

Also allow users to turn it off by adding an option
spacemacs-show-trailing-whitespace.

tsonntag/dotemacs,tsonntag/dotemacs,tsonntag/dotemacs,tsonntag/dotemacs