New Command Line Option -f

Offer a new command line option "-f" / "--filelinks" that links all bibtex-entries with the bibtex-named PDFs that are found in the respective directory. (this is ALT+f for a single entry in the GUI.)

Example application

jabref -f -i input.bib -o output.bib

The new option will simplify batch-processing.

Feature Generalization

Enable ALT-f not only for single entry, but for a selected subset of entries (as CTRL-g).