fix(reducer): Fix stateID increment & build deltalog on server only

[delucis]

Fixes #795

The move reducer currently increments _stateID before events (and other plugins) are processed, potentially resulting in deltalogs as follows:

[
  { action: { type: 'MAKE_MOVE' }, _stateID: 2 },
  { action: { type: 'GAME_EVENT' }, _stateID: 3, automatic: true }
]

This was causing bugs on the client, because the next move might produce a deltalog like:

[
  { action: { type: 'MAKE_MOVE' }, _stateID: 3 }
]

This is filtered out by the client because the _stateID is considered stale.

This fix ensures that _stateID is only incremented after plugins run, so that log entries for a single action all share the same ID. For multiplayer clients, events aren’t run locally, so we can’t send an optimistic deltalog here, because the “automatic” events would now be filtered out, so instead, deltalog is now only produced on the master (for multiplayer clients).