Simplify/refactor operators

The partitioning code and tiled model are refactored along to the description in the ParaPhrase deliverable D6.8 (chapter 4).
I fixed a bug which sometimes caused losing agents. Now there is an issue with deadlocking (#1) but it's not a bug.

The tile version divides the world into 2 pieces, and it requires the width to be even.
It might be an error. It all depends on model definition, about which to be honest we (I to be exact) don't care too much. Wright now we put more interest in partitioning and paralyzing.  Model itself will evolve later (up to Foraminifera I guess).

That said, we will try to update direction even without move.