Don't lose items_without_deps

After a worker has finished, its item is removed from the list(s) of
dependencies. This step completely misses "items_without_deps", though,
so we lose all those items.

This problem is much more likely to show up if "workers = 1".
format_node_result only takes one argument
Add missing quote
Merge pull request #6 from vain/minor-fixes2

More minor fixes
Add pho to AUTHORS
Merge pull request #5 from vain/lost-items

Don't lose items_without_deps