Way to insert links that open in new tab

[sbarratt]

I've made it so that if you start a link with \/, it opens it in a new tab. I've done this by adding the lines

    if link[:2] == '\\/':
      link = link[2:]
      newtab = True
    else:
      newtab = False

and then the lines

    if not newtab:
      b = b[:m.start()] + r'<a href=\"%s\">%s<\/a>' % (link, linkname) + b[m.end():]
    else:
      b = b[:m.start()] + r'<a rel=\"noopener noreferrer\" target=\"_blank\" href=\"%s\">%s<\/a>' % (link, linkname) + b[m.end():]

to the replacelinks function which seems to work well.

What do you think about adding this to master? What would be a good way to signify new tab?