[BUGFIX] _languageUid property not set on insert

The patch ensures new objects are created with default language only.
Database field and object property are set properly to 0.

Furthermore the language uid is set only if not set before from outside.

Resolves: #65363
Resolves: #65364
Releases: master, 6.2
Change-Id: Ifc777e482ef12dba46938f826548a97758e531a1
Reviewed-on: http://review.typo3.org/41595


Reviewed-by: Nicole Cordes <typo3@cordes.co>
Tested-by: Nicole Cordes <typo3@cordes.co>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Daniel Goerz <ervaude@gmail.com>
Tested-by: Daniel Goerz <ervaude@gmail.com>
Reviewed-by: Morton Jonuschat <m.jonuschat@mojocode.de>
Tested-by: Morton Jonuschat <m.jonuschat@mojocode.de>