Add basic markup editor

- The editor loads the markup into a textarea and saves the value
  of the textarea as the new markup of the page. Then it reloads
  the page.
- There are two methods of editing:
  + Hover over an editalbe element and click the `Edit` link that
    appears.
  + Highlight some text and click the `Edit' button that appears.
- Searching rendered text in the markup is and will always be
  rudimentary.
Fix messed up pathes on search results page
Update `README.md' and `welcome.md'