Sort out the cell load problem
Load all cells on startup vs. load cells on demand.
Currently we are doing the later, which leads to some errors in script execution. But the former might be to expensive, so we should go for a hybrid solution (only load enough data from each cell to satisfy the script system and load the rest on demand).
(RM-28 from redmine: created on 2011-08-06 by Lukasz Gromanowski, , closed on 2011-09-24 by Marc Zinnschlag, blocks #29 (closed))