Added Polish translation
Updated Polish translation
Let's save bibtex entries sorted

Now we save bibtex entries sorted by the entry key. It helps to
keep the database file 'ordered'. It may be useful if somebody
wants to track the file in version control...
Fixes SF bug #92.
Cleanup of old stuff
Fix a Callback issue
Add Cancel button to the confirm dialog

Once upon a time... the confirm method for closing modified
documents was changed. Closing the window one could only
close with or without saving. Now it's possible to cancel
the operation and recheck the document.