DropIt v8.4

This is a release with some improvements and fixes. This is the complete list of changes:
- added "Print" action (using default system applications based on file formats)
- added %Pages% abbreviation to read the number of pages of a document
- added %YearWeekCreated%, %YearWeekModified%, %YearWeekOpened%, %YearWeekTaken% abbreviations
- added option to configure FirstFileContentDate abbreviations for different languages (read 5.6 of the Guide)
- updated the internal tool to manage archives (7z v16.04)
- fixed ++ and -- modifiers to work properly with all Unicode characters
- fixed some abbreviations that use Windows Explorer information to work on Windows Vista/8.1/10
- fixed support to use pipe symbol in regular expressions in Additional Filters
- fixed some minor bugs