[TASK] Add latest changes to ChangeLog.txt

In preparation of the Alpha2 release of TYPO3 CMS 6.2 the latest
changes in extbase were added to the ChangeLog file.

Releases: 6.2
Resolves: #49896
Change-Id: Ib59f741a4427ba093e459545c823f9bfd0277d5e
Reviewed-on: https://review.typo3.org/22203
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters
Reviewed-by: Anja Leichsenring
Tested-by: Anja Leichsenring