Currently the `setext` scanner and parser code uses an EMF-based position class for storing file positions. The consequence of that decision is that all applications that parse an input file using a `setext` generated scanner and parser must import EMF. To make such applications easier to port to a different environment, a new common position class is introduced, thus moving the decision for using the EMF-based position class to the AST tree building code instead. Addresses #307 #43