Fix typo to clarify comment.

Change-Id: Ibddc2f5a4bccfb2dc71962c8d3d81232b03ff9c6
Support meta teams when checking match entrants.

None and "???" are valid in the listing, but shouldn't be considered
for anything else. In particular, they can appear several times
and won't be in the overall list of teams.

Change-Id: I3af162863ab536be39bba2f4a2e75d5f37621585
Rename a test function to avoid clash.

Not sure how this occured, but it's presumably been like this for
ages. Also fix the test which this had hidden.

Change-Id: Ib43ae100b37a4b904cadd324e50685cb67db8991
Support empty corners in the scores for a match.

But not unknown teams. Also bump the dummy state to include some
empty corners in the right format now we support them fully.

Change-Id: If9f79c46a5a2752988a93a76fac87b26889ff4c0