Release 0.5.1

Features

• ts: install parser if not installed in correct location (dca37ff)
• health: report any conflicting parsers (52ff9cf)

Bug fixes

• agenda: make spans work like emacs (#915) (88c71f3)
• ts: correctly highlight table headings (#914) (4a405fb)
• links: allow any value after http protocol (e5b800e)