added Helpers.createMap()
added Argument.filterExplicit()/filterImplicit()
added ParamsPool
added handling of implicit arguments to ArgumentNodesCreator
fixed DefinedFunctionsCreator to correctly use Argument.explicitArg()/implicitArg()
fixed Argument.explicitArg() to check that name is not null
fixed style in DefinedFunctionsCreator
changed grammar to allow implicit arguments
refactored FileSetSmoothTest, FileSmoothTest to make use of implicit argument assignments