D370: templatefilters: add `reldate` for human-style relative dates

[phillco (Phil Cohen)]

phillco added a comment.


  Heh, whoops. It didn't come up for searches of "relative" or "relative date".
  
  I'll abandon this revision but the one right before it is probably still worth including.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D370

To: phillco, #hg-reviewers
Cc: akushner, mercurial-devel