In includePrerelease mode, there are in fact versions less than 0.0.0
which will satisfy the range <0.0.0.

Append a `-0` prerelease tag on the parsed comparators when in
includePrerelease mode.  Otherwise, 2.x will be satisfied by 3.0.0-beta,
since it's in `>=2.0.0 <3.0.0`.  However, `2.0.0-beta` will _not_
satisfy this range.

By appending the `-0`, the version set is pinned to the appropriate
boundary.

Note that doing this in non-prerelease-including mode would be a
mistake!  Appending the `-0` to the comparator means that prereleases in
the tuple are allowed, so `2.0.0-beta` would match `2.x` in
non-prerelease-including mode as well.  However, if we're including
prereleases, then their inclusion is intentional.

Fix: #282

Close: #248

NYC doesn't like to cover things that don't have file extensions

The next major version bump should change the opaque arrays into actual
objects with keys.  But at least in the meantime, we can provide a
mapping of keys to the array indexes.