fixes #51744

Prepared the My.Jdownloader API for Text Diff Requests. This is not fully functional yet, but can easily be extended if required.

Better key collapsing for the Download Events. Dupe Events will be avoided if possible now.

build>full

git-svn-id: svn://svn.jdownloader.org/jdownloader/MyJDownloaderClient@27007 ebf7c1c2-ba36-0410-9fe8-c592906822b4