Fix indenting of HTML (closing) tags for instance. Fix #1294

The indentation level is not anymore reduced by adding a new line,
which previously caused multiple reductions of the indentation level.
This fixes the behavior of HTML closing tags, which currently
"jump" backwards if you try to move them down.
Merge pull request #2164 from steffengy/fix-indent

Fix indenting of HTML tags for instance. Fix #1294