Lock, purge and cancel TickTask in onEnable.
Have TickTask be locked from the start.
Clear lag spikes if system time ran backwards.
Also remove data for CheckType.ALL for components that don't implement
IHaveCheckType.
Tests are put into test/... not main/...
Imports fail.
Clear NCPExemptionManager in onDisable just in case.

Little significance, but could be expected to have some future purpose.
ActionFrequency.update: reorder safety checks slightly.

Gains a little bit of consistency for negative time differences. Also
might be faster for the case of seldom shifting, though most likely
by an insignificant amount.
Add more tests for ActionFrequency.