changeable RefineFunctor

[LucasDworschak]

In the last meeting regarding the vectorlayer project we came to the conclusion that we would need a refineFunctor that uses maxDistance instead of minDistance to the bounding box.

In order to use this functor effectively, it must be possible to change/define the refinefunctor at scheduler initialization.

[adam-ce]

evaluate, whether maxdist (error lower bound) is usable for textures. if so, just keep it.