Refactoring in ChiSquaredModule and FitSuiteObjects to have isgisaxs like chi module, unit test for chi module

Replaced vector of pointers to axes inside OutputData to vector of objects; removed getAxes() method from OutputData

N of free parameters in ChiModule, scale for max intensity in FitObjects, more tests in TestIsGISAXS12

Fixed bug in InterferenceFunction2DParaCrystal; fixed warnings about size_t -> int conversions; updated Xcode project file

Made OutputDataIterator more accessible fro use with other containers: TContainer should now only provide indexing access (overload operator[], also for const) and return its size through size() function