Remove useless conditions that check invalid input

In `CommentAutoIndentStrategy` the conditions that check if the input is
correct are useless because the docs don't state that invalid input can
be passed. While for Eclipse docs this doesn't mean anything all the
other auto edit strategies had never had any problems with invalid input.
Add auto breaking of comments functionality

With this feature multi-line and Scaladoc comments are automatically
broken after the print margin.

The feature can be enabled/disabled in `Scala -> Editor - Typing`.

Fixes #1002101
Merge pull request #682 from sschaef/t1002101-auto-breaking-comments

T1002101 auto breaking comments