Added input file support to ixslt
* a single file may be passed to the XSLT processor as input
** the file is read once and stored within a xalan::XalanParsedSource to be reused by all calls to "TransformationFacade::generate"
* added appropriate TranformationFacade constructor overload
** this new constructor overload which is taking a path to both the transformation and the input file is the main constructor
*** the old constructor is now only a alias for this new constructor
* adapted static "try_create" TransformationFacade factory method into variadic template factory method
* added optional "--input" argument to ixslt
** expanded option handling accordingly