.change, .increase, and .decrease wrong assertion type

[meeber]

These three assertions are all registered as chainable method assertions despite not having any chainable behavior. It'd be okay for them to be chainable if they had non-specific meaning like "of" and "at", but that's not the case. Therefore, they should be changed to normal method assertions.

I suspect they were registered as chainable method assertions because of their interaction with the by assertion, e.g., expect(targetFn).to.increase(subjectFn).by(2). However, that's still normal method assertion behavior; it'd only be chainable method assertion behavior if the non-invoked property-access version of the assertion had a side-effect.