Update Changes
Clearing now clears back to the initial argument

If you do

    run_tests "Foo", [qw(main)], { autocleared_thing => 20 };

then `autocleared_thing` will be cleared to 20, not to its default
value (or undef given no default). Which is nice.

TODO:
  * Document changes
  * Make { autocleared_thing => builder sub { [] } } work.
Tidied autoclear.t up

Tried to make the autoclear test know a little less about what it's
expecting to be set in the attributes.
Made dzil happier
Documentation is a good thing

Even the kind of documentation I write is better than no documentation
at all. Documentated the new reset logic.