5.8.0 -- Fix #26, fix #27, add route-cell macro, update deps

- Old `route-cell` function in the `tailrecursion.hoplon.util` namespace
  is superceded by the new `route-cell` macro in `tailrecursion.hoplon`.
  The old one is now deprecated.

- Fix #26: The :scroll-to attribute now works correctly in FireFox.

- Fix #27: Formula cell child can now support formula cells containing a
  list of elements and not just a single element.