[TASK] Prevent PHP warning in AbstractMenuObject

If the current page can not be retrieved for the language menu
the menu generation will be skipped to prevent a PHP warning
in the array_merge() call.

Change-Id: I16c1cc171a6f9aee13294a6e1ed14ce8ac492a17
[TASK] Improve linkvalidator scheduler task usablity

The getAdditionalInformation() method is implemented in the
linkvalidator scheduler task to show more information about
the task in the scheduler Backend module.

Resolves: #61198
Releases: 6.3
Change-Id: Iebb43923b73ff4ecebab4a6747655596be859604
Reviewed-on: http://review.typo3.org/32383
Reviewed-by: Alexander Opitz <opitz.alexander@googlemail.com>
Tested-by: Alexander Opitz <opitz.alexander@googlemail.com>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
[FEATURE] Provide TSConfig to link checkers

The currently active TSConfig for the linkvalidator is passed
to the LinkAnalyser instance which makes it publicly available
for the link checkers.

Resolves: #54518
Releases: master
Change-Id: I59d1de5fb3f818d340f499260589edf9a45d3148
Reviewed-on: http://review.typo3.org/26499
Reviewed-by: Markus Klein <klein.t3@reelworx.at>
Tested-by: Markus Klein <klein.t3@reelworx.at>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>>
[FEATURE] Report links to disabled linkhandler records

A new TSConfig setting is introduced to mod.linkvalidator that is called
linkhandler.reportHiddenRecords.

If this setting is enabled an error will be triggerd in the linkhandler
link checker if a linked record is not enabled.

Resolves: #54519
Releases: master
Change-Id: Ib95cff1f9bdc67b0636cf38e6d9f33a8cbbdff75
Reviewed-on: http://review.typo3.org/26503
Reviewed-by: Markus Klein <klein.t3@reelworx.at>
Tested-by: Markus Klein <klein.t3@reelworx.at>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
[FEATURE] Reusable getCategoryFieldsForTable itemsProcFunc

Allow the usage of the method
\TYPO3\CMS\Core\Category\CategoryRegistry->getCategoryFieldsForTable
that can be used as itemsProcFunc for select fields in the TCA in
multiple context by introducing a new categorizedTable configuration key
in the config section of a column in the TCA.

This configuration key can either consist of a single string containing
the name of the table or a configuration array to define additional
conditions that need to be true so that a configured table is used.

Resolves: #53045
Releases: master
Change-Id: I128cbeb6747a8f83e68cdaaaafbc3ab5901353d4
[FEATURE] Allow appending of element browser mounts

A new User TSconfig option is introduced that allows the alternative
element browser page tree mounts to be appended instead of beeing
replaced:

options.pageTree.altElementBrowserMountPointsAppend

Resolves: #50780
Documentation: #63009
Releases: master
Change-Id: I2a0b616b398131684a2c7c71a25b4b51ef6f0c50
[FEATURE] Introduce read-only column for file mounts

File mount records get a new flag "read only".
This flag replaces the virtual flag introduced earlier,
so it can be defined natively in the record.

Resolves: #59830
Releases: 6.3
Change-Id: I11c738cb4740ea20b9088cc796ea0fb7ced1107a
[WIP][BUGFIX] Language overlay for displayCond / subtype

Before a displayCond field value or the subtype_value_field value is
used a language overlay is performed to make sure that the l10n_mode
configuration is taken into account.

WIP: language overlay for subtypes.

Resolves: #59130
Releases: 6.2
Change-Id: I0fdcdcb86e6201f454f8b6ede3ee519f53da8ff1