[!!!][TASK] Raise version to 1.4.0-dev

Extension is not compatible with TYPO3 < 6.0 anymore.
This ensures EXT:restdoc may be used with TYPO3 7.0 together
with EXT:sphinx v2.2.0-dev.

Change-Id: I1736aa325eb0a864bf3b6a69525b41cde577e82b
Reviewed-on: http://review.typo3.org/33946
Reviewed-by: Xavier Perseguers <xavier@typo3.org>
Tested-by: Xavier Perseguers <xavier@typo3.org>
[!!!][TASK] Remove deprecated code

Change-Id: If230d17e6188d2805d6f5f8d62e869f42ec5bd52
Reviewed-on: http://review.typo3.org/33947
Reviewed-by: Xavier Perseguers <xavier@typo3.org>
Tested-by: Xavier Perseguers <xavier@typo3.org>
[!!!][TASK] Remove support for TYPO3 6.0 and 6.1

Change-Id: Ic2d99847074b1f40a7c1a70aaef99f7bb15b4eb6
Reviewed-on: http://review.typo3.org/33957
Reviewed-by: Xavier Perseguers <xavier@typo3.org>
Tested-by: Xavier Perseguers <xavier@typo3.org>