Improve efficiency of quadrature based estimation

[PhilippSchuette]

With the current status of argument estimation there is exactly one estimator capable of higher moments: QuadratureEstimator. Right now, this estimator re-calculates function values for every concrete moment order requested. This is quite inefficient as function values f'(z) / f(z) could quite easily be reused between different moment orders.

Implementing this reuse is mostly a matter of storing previously calculated function arrays in internal caches without too much additional overhead in the case where only the zeroth moment is required by some concrete FinderAlgorithm.

Note that this is quite distinct from the internal caching used in SummationEstimator because we retrieve function values on the exact complex line segment currently considered!