* e.g. member functions defined in the class definition are implicitly marked `inline`

* i.e. InputXSLT now requires a C++14 supporting compiler / standard library implementation
* this was done while enabling the StreamInputSource to handle all kinds of streams
** this in turn is required to enable e.g. stdin as transformation source while preserving the correct filesystem context

* in difference to ErrorCapacitor this class doesn't throw an exception on "discharge" but returns the gathered warnings
* adapted FunctionTransform and frontend error handling to include warnings
* added static "try_create" method to TransformationFacade
** wraps construction error handling
** custom logic may be embedded using the std::function argument
*** this was implemented to prevent unneccessary code duplication for handling both construction and generation errors
* adapted FunctionTransform to return warning as "warning" nodes in the result tree
** added functional lambda expression factory method "handleErrors"
*** returns a error handling lambda expression for a given ResultNodeFacade
* implemented WarningGuard class in frontend executable
** guarantees warnings to be printed to std::cerr independent of any exceptions

* ErrorMultiplexer is derived from both xercesc::ErrorHandler and xalan::ProblemListener
* registers itself as XalanTransformer's ErrorHandler and ProblemListener
* distributes captured errors and warnings to all registered ErrorMultiplexer::Receiver instances
** ErrorCapacitor implements the ErrorMultiplexer::Receiver interface and as such registers itself in a given ErrorMultiplexer instance
** ErrorMultiplexer reduces the different xalan and xercesc internal error classifications into either warnings or errors
* this was implemented to make it possible to easily differentiate between warnings and errors
** previously warnings were treated as errors
** ErrorCapacitor ignores warnings and only captures errors
** WarningCapacitor will be implemented to handle warnings during XSLT processing