Draft: #316 Introduce small common position class in scanning and parsing

To avoid a forced connection between parsing a text file and having to import EMF, a very simple CommonPosition class is introduced without additional dependencies if so desired.

I have no errors, and I can build it locally. The number of files that it touches is somewhat insane, but changes are generally easy. A perhaps somewhat tricky part is whether I made the switch from CommonPosition to Position always at the right spot. At times I made life easy by adding an overload to a commonly called function, such as error reporting.

What may be incomplete are the manifest dependencies of some plugins, perhaps some position.metamodel bundle imports are no longer required.

Closes #316 (closed)