* Moves /datum/var/signal_enabled to datum flags
`signal_enabled` is a variable on /datum, so present almost every object
in the game. Folding it into the existing `datum_flags` variable will
save allocating a variable on every datum in the game.
- Clown weaponry was using the `signal_enabled` variable to turn their
attached slippery component on and off when the shield/sword was
toggled. They now just remove/add the component, rather than touching
deep datum internals.
6370ee6522