Minor improvements to aged_containers (RIPD-363)

- Added unit tests for element erase
- Added unit tests for range erase
- added unit tests for touch (const_iterator)
- Un-inlined operator== for unordered containers
- Fixed minor problems with ordered_container erase()
- Made ordered_container...
  - erase (reverse_iterator pos) not compile
  - erase (reverse_iterator first, reverse_iterator last) not compile
  - touch (reverse iterator pos) not compile
- Verified that ordered container...
  - insert() already rejects reverse_iterator
  - emplace_hint() already rejects reverse_iterator
that is a great question and one that Vinnie, Howard, and I thrashed with for a while.  Here's the argument as I understand it: it's okay to delete something that is const.  Const things are deleted all the time when they go out of scope.  It's interesting to think about.  The reasoning is interesting.  I'd be a lot more worried about this if Vinnie and Howard had not agreed that it's the right thing to do.