Introduce a null iterator factory to provide an end iterator for the intersection iterator.
Implement the leaf iterator completely analogously to the level iterator except it also finds
different level  neighbors. If the starting entity is not on the leaf this now correctly returns
an end iterator. This also simplifies the code (no extra obscure pushleaffacet function).

Each intersection has only one neighbor in the current implementation. Faces can have more neighbors.

Make entities default constructable using the new null iterator factory. Adapt other classes to make the foamgrid tests compile.

Make their constructors private and only accessible by the Interface class or the
related iterator.

Return an entity from the subentity method instead of an entityPointer implementing the new interface.

Timo Koch authored 9 years ago and Timo Koch committed 9 years ago

- Make entities only coarsen if the other children of the father are leaf entities
- Remove levelschanged set and iterate over all levels to erase old pointers and vanished entities
- Remove some old debug output

Timo Koch authored 9 years ago and Timo Koch committed 9 years ago

Add some asserts

This is fulfilled automatically in regular FV methods, but in network situations
this may be violated.

The result looks better than previously -- not sure whether it is correct, though.