Improvements to documentation etc. in preparation for v3r5

• Fix licences and Doxygen in pole, nonresonant form factors, and rescattering line shapes
• Add reference for pole line shape
• Fix class names and add Doxygen to LauCalcChiSq, LauResultsExtractor, LauMergeDataFiles
• Update Doxyfile with more recent Doxygen version
• Make consistent the use of ClassDef and ClassImp everywhere