Detect reachability fixed point of CIF data-based synthesis sooner

Currently, the org.eclipse.escet.cif.datasynth.CifDataSynthesis.reachability method detects a fixed point for the reachability loop at the end of each iteration. However, if we have 100 edges, and the first edge in an iteration leads to the fixed point, we need to consider the remaining 99 edges for the remainder of that iteration, and we need to consider the 100 edges for a complete next iteration, until a fixed point is detected. This can be improved. We can just count the number of edges that did not lead to changes. If we reach the number of edges, we have reached the fixed point. Then instead of 100-199 edges being applied without change, we only get 100 edges being applied without change. This can thus save either no work or an entire iteration, or anything in between.