Renamed pref key for custom shell plus clean up of not used prefs #750

sed -i 's/nightly.xml/version.xml/g'

fix #113: dmg is now signed

remove unused entry edit_bookmarks_dialog.location from dictionary files

fix #604: fix truncated search results when searching root folder

Better support of XFCE

store credentials to Google Drive in GoogleDriveClient

minor changes in the readme file