Remove requirement for Convert Line Breaks filter.
- Removed validation errors if "Convert line breaks" filter not enabled.
- Removed checks for filter order of "Convert line breaks" filter.
- Added warning if "Convert line breaks" filter enabled.
- Added warning if
<p>and<br>not in allowed HTML tags. - Removed "Convert line breaks" from default "Markdown" text format.
- Added
<p>and<br>tags to default "allowed" tags. - Updated tests. Closes #3530290