Added better handling of secretion on multi-core machines when only python based secretion is enabled. listing secretion data inside secretion plugin will cause big slowdown of the program. The slowdown is even worse with multiple processors. This has to do with necessity to synchronize between threads when executing secretion i.e. we have to make sure that only one thread executes secretion and because we do the checks every pixel copy attempt we get really bad performance with multiple cores.The bottom line: this plugin shuld be only used to implement custom secretion i.e. on a per-cell basis. Secretion by type should be specified in the PDE solver. REMARK: Secretion plugin is to be used to do "per cell" secretion (using python scripting)
Added error handling to fieldSecretor functions. When PixelTrackerPlugin or BoundaryPixelTrackerPlugin are missing exceptinos are thrown to let user know about possible malfunction