Summary: Fixes T10381. When we converted to `PHUIRemarkupView`, some instructional text got linebreaks added when it shouldn't have them (the source is written in PHP and wrapped at 80 characters, but the output should flow naturally). Fix this so we don't preserve linebreaks. This also makes `PHUIRemarkupView` a little more powerful and inches us toward fixing Phame/CORGI remarkup issues, getting rid of `PhabricatorMarkupInterface` / `PhabricatorMarkupOneOff`, and dropping all the application hard-coding in `PhabricatorMarkupEngine`. Test Plan: - Grepped for all callsites, looking for callsites which accept remarkup written in `<<<HEREDOC` format. - Viewed form instructions, Conduit API methods, HTTP parameter edit instructions. Reviewers: chad Reviewed By: chad Maniphest Tasks: T10381 Differential Revision: https://secure.phabricator.com/D15963