Add task to clean up DB inconsistencies: container and children with different languages

[sypets]

I split up issue #58 which contained both case to make it easier to handle.

The following inconsistencies should not happen and will cause elements to disappear (in list and page view):

• elements in a gridelements container have a different sys_language_uid than the container

how inconsistencies might happen

For example, if users copy exsting gridelement with children to a column with different translation (using copy, insert, not translate button).

SQL

Find existing records:

SELECT tt1.uid,tt1.pid,tt1.header,tt1.sys_language_uid,tt2.uid,tt2.header,tt2.sys_language_uid 
  FROM tt_content tt1 
  INNER JOIN tt_content tt2 
    ON tt1.tx_gridelements_container = tt2.uid
  WHERE  not tt1.deleted 
    AND NOT tt2.deleted 
    AND tt1.tx_gridelements_container > 0
    AND tt1.colpos = -1
    AND tt2.ctype = 'gridelements_pi1'
    AND tt1.sys_language_uid != tt2.sys_language_uid
    AND tt1.sys_language_uid != -1
    AND tt2.sys_language_uid != -1;

fix:

UPDATE tt_content tt1 
  INNER JOIN tt_content tt2
    ON tt1.tx_gridelements_container = tt2.uid 
  SET tt1.sys_language_uid = tt2.sys_language_uid
  WHERE  not tt1.deleted 
    AND NOT tt2.deleted 
    AND tt1.tx_gridelements_container > 0 
    AND tt1.colpos = -1 
    AND tt2.ctype = 'gridelements_pi1' 
    AND tt1.sys_language_uid != tt2.sys_language_uid 
    AND tt1.sys_language_uid != -1 
    AND tt2.sys_language_uid != -1;