DropIt v6.1

This is a release with some improvements and fixes. This is the complete list of changes:
- improved interface and performance
- improved "Define Abbreviation Value" window
- improved "File Already Exists" window
- improved "Select Action" window
- interrupted 64bit version (32bit version works on all systems)
- added option to "Auto-hide target image on the left of the screen"
- added option to "Ignore files if their size is changed after loading"
- added support to filter by file content for PDF format
- added support to press "Ctrl" key while folders are dropped on to add them as Monitored Folders
- added support to Upload using FTP Passive Mode
- added support to use abbreviations in Rules
- fixed issue of automatic update under 64bit systems
- fixed issue of disappearing target image after standby/suspension
- fixed issue reading lowercase abbreviations
- fixed issue using %SubDir% abbreviation when the option to decide if scan subfolders is disabled
- fixed some minor bugs