github.com/sdboyer/gps

Fixes #218.

If the input includes required packages that are mains (as it's intended
to support), then excluding mains will end up causing failures. Duh.

Should fix golang/dep#366.

I don't know what I was originally thinking, here - there's no way it
could ever have been correct to insert the original path into the trie.
The additional subpath caused only cached results to be incorrect, as
subsequent calls would find the longer/subpath in the trie, and return
that out erroneously as a root.

This also changes all deduction tests to run twice in order to ensure
we're testing both the cached and uncached paths.

Fixes #217.

Makes for slightly cleaner call sites (no matter how few), and obviates
the need for the ugly no-op _private() method.

With the preceding change to solver test output, the default output mode
is now more desireable.

It's a sad day when we have to disable a good test. Need to fix these
concurrency issues, ASAP.

Fix up docs just a bit more

This was causing potentially unnecessary network activity, as well as
placing a block that effectively serialized slow points in the solving
algorithm.