Move targets are now intended to be +1 +2 +3 for foes. The old syntax
of using 1 2 3 is still supported, but is not recommended.
(The old syntax will still be used in the old client, but the Preact
client will support the new syntax going forward.)
This makes the difference between move number and move target
clearer.
This also fixes the Conversion 2 ambiguity (although for backwards
compatibility, we do still need to special-case it).
It turns out not creating a format on-the-fly breaks deserialization.
We now just use the same custom-rule system that tournaments use.
Some hacks are currently necessary (many tests assume that we're
playing in Anything Goes rather than Custom Game) but we'll work them
out in time.
