Version 1.3.0 released.

Changelog:
1.3.0
-Main window: added option to open data files save location
-Main window: added option to import xml file
-Main window: volume add button is now disabled during cataloging
-Main window: volume properties additionally displays number of files, folders, catalog data file name, size and location
-Progress window: added path to currently analysed sub-folder
-About window: e-mail address can be clicked to send an e-mail using default mail client
-Main window+search window: size is now displayed in a more elegant way
-Search window: new look
-Fixed incorrect search window display under linux
-Fixed lack of file and volume sorting on linux (listfiles java function lists folder contents unsorted on linux with openjdk so added own sorting)
-Some minor tweaks and bugfixes