Revert "Stop isn't safe to call from devices thread"

This reverts commit 372b0fa15b5f32654a0d78ea21b676b3e883d0e1.
Revert "Update the other Schedule function as well"

This reverts commit d6c03ce205ec60d1e2690adf68ef803ba654da8b.
Revert "Allow modules to schedule themselves after the Broker has stopped"

This reverts commit a9deaecd7518ba546797da3679a5e172df713f06.
Revert "Don't allow modules to schedule themselves when stopped"

This reverts commit 6a53bd44c35dcb6825f7dc82757e7cc17f680f77.
Revert "LB: implement Stop()"

This reverts commit e0a356622c4b5f999404dc62bd2507ab169b652b.

This commit is useless as Broker::Schedule now handles this (and much
more effectively).
Revert "Broker now stops modules before quitting"

This reverts commit 72cfb08e2053bcc835e0fb505060acaa6e5a01c4.

There's no point in having this if modules are not currently registering
Quit functions.
Don't allow modules to schedule themselves after stopping

Fixes #244