[RELEASE] Release of TYPO3 4.5.26rc1

Change-Id: I3497e1cd620e6ed0ca49c6d143580a48cdcb501d
Reviewed-on: https://review.typo3.org/20085
Reviewed-by: TYPO3 Release Team
Tested-by: TYPO3 Release Team
[TASK] Set TYPO3 version to 4.5-dev

Change-Id: I67350696542cfd9a96f2d711e7349e6ea89a08dc
Reviewed-on: https://review.typo3.org/20086
Reviewed-by: TYPO3 Release Team
Tested-by: TYPO3 Release Team