Fixes 11544: Add color: inherit; to .panel-title to ensure proper text color when customizing @headings-color. Fixes 11515: Reorder the headings with body text and text emphasis classes

BS3 commits: 21e2ae94897376ff0303144a703f7eb54be9bf3c,
d2f8b5327b36b9a9839d595070d841146aa4c6ab