Fixed issue in implementation of #326 Changed the vector name creation method for the multi-argument methods
Fixed issue #330 "Files still cannot be saved in some cases"
Fixed issue in implementation of #326 Multi-argument functions are now only replaced, if they are surrounded by parentheses from both sides.
Fixed issue #329 "'interpolate' masks 'steps' in plots"
Fixed issue #328 "Cache headlines disappear after deleting part of the cache"
Fixed issue #327 "Comment sequences in strings are interpreted wrong"
Fixed issue in implementation of #326 Improved parentheses handling
Fixed issue in implementation of #326 Added check for strings
Implemented ticket #329 "Create multiargument function methods for data sets" (Refactored part of the code on-the-fly)
Implemented tickets #239 #240 #241 #242 #243 "Add the zeta function" "Add the beta function" "Add the clausen function" "Add the dilogarithm" "Add the digamma function"