Revert "[BUGFIX] Distinguish unassigend columns and colPos 0"

TYPO3 4.7 is in extended maintenance mode, which actually means
only security fixes and blocking fixes upon RM approval.
This one was explicitly dissapproved.

This reverts commit 542bd7da494082637733ca69909289d1bb9c3479

Change-Id: If870e4e155e0733c57d62b69ea5be297d7691b45
Reviewed-on: https://review.typo3.org/25704
Reviewed-by: Steffen Ritter
Tested-by: Steffen Ritter