Rework OmniTracker pinned messages

[TheCraiggers]

Problem: Even though trackers are pinned, they get buried and nobody looks at them.

Instead of a single pinned message, always display the current tracker after each command and delete all previous trackers. This way you can always tell at a glance what the game state is and there's not a ton of spam.

This also solves the problem of people typing commands in multiple (perhaps wrong) channels, and people getting confused about the gamestate because of the out-of-date non-pinned messages sent in response to commands.