DropIt v8.3

This is a release with some improvements and fixes. This is the complete list of changes:
- improved performance reading file contents
- added %FirstFileContentDate% and %FirstFileContentDateNormalized% abbreviations to get the first date in file content (normalized as YYYYMMDD)
- added %FileContentMatch1% to %FileContentMatch9% abbreviations to use text from file content in destinations
- added %Keywords% abbreviation to get supported file keywords
- added 7ZIP as new standard algorithm for Encrypt and Decrypt actions
- added Additional Filter of file content to a full powered regular expression filter (and removed regular expression support in Literal string filter)
- added "regex(p1,r1)" abbreviation modifier to replace all occurrences of the regex pattern p1 with regex replacement pattern r1 (matched groups are referenced by \1-\9)
- fixed limit of compression password length
- fixed support to use image abbreviations for TIF and CR2 images
- fixed some minor bugs