Release 3.9

This is a release with important improvements and fixes. This is the complete list of changes:
- improved automatic update (manually update this version to start with the new method)
- improved interface (thanks to Leif)
- improved support to HTML themes (thanks to tpr)
- improved support to manage duplicates
- added checkboxes for monitored folders
- added lightbox preview to open images of HTML lists
- added some internal environment variables
- added support to duplicate profiles
- added support to special actions as Command-Line parameters (using "/Key")
- removed Alt + FirstButtonCharacter support (due to compatibility problems)
- removed Context Menu integration (due to compatibility problems)
- fixed internal context menu issue with Windows Classic theme
- fixed minor bugs