Release v0.3.1

Changed

• Start button and menu option Start analysis - will be set to disabled if you do not provide nessus files during the next selection (e.g. cancelling nessus files selection, cancelling source directory selection, selecting directory without nessus files, dropping files with extension different than .nessus, dropping directory without nessus files)
• List of files to pars - will be correctly cleared out if you do not provide nessus files during the next selection (e.g. cancelling nessus files selection, cancelling source directory selection, selecting directory without nessus files, dropping files with extension different than .nessus, dropping directory without nessus files)