[FEATURE] Add missing checks for white lines to the sniffs

This adds checks for:
* Non-empty comment
* Opening comment tag must be only content on the line
* Closing comment tag must be only content on the line
* Additional blank lines at the end of comment
* Missing short description
* Short description must be on first line after comment open tag
* There must be a blank line between short description and long description
* Short and long description must start with a capital letter
* Short and long description must not start with a non-letter char
* Short and long description are threaten in Unicode
* There must be a blank line before comment @ params

Resolves: #396