Add column holding the filename of last file used for updating reporter annotations

[Nicklas Nordborg]

This is to simple let everyone know where the annotations are coming from. This should be added as a string column on a similar footing as the 'lastUpdate' column. Plug-ins must of course let the core know about the filename, so it can only be made semi-automatic. A possible (and easy) way is to create a ReporterBatcher.setFilename() method. Plug-ins should call this method to automatically let the core set the filename. Null is an allowed value.

Note that the column should only hold the filename. It is not a reference to a file on the BASE file system, because foreign keys in the reporter table are only good for decreasing performance.

Some issues:

• Should the core reset the value if a plug-in never calls the method or should it be left unchanged?
• What if a reporter is manually updated from the web interface? Maybe we could store the name of the user in this case?
• Users should also be aware of that a plug-in may only update a few columns, which means that some annotations may come from one file and some from another file.

NOTE! Do not forget to update the UML diagrams and documentation!