Implemented support for modifying external function base path
* one expects a read-file function to work relative to the directory the transformation is located and not to the executable's location
** from the perspective of the user the transformation is the application, not the actual executable
* removed PlattformGuard struct from TransformerGuard (now TransformerFacade)
* TransformerFacade is instatiated with the appropriate relative working path
** i.e. it will have to be instantiated for every directory containing one or more transformations