Fixes #8116: Error-Dialog - Button for FE element is broken. First problem: replacing '\n' with '<br>' failed for FE link. Second problem: FormEditor fixed in case missing {{formId:S}}.

Fixes #3992 (Feature): dbNameQfq & dbNameData already implemented. dbNameT3 renamed from T3_DB_NAME. No more configuration in config.qfq.php necessary. Manual updated.
AbstractException.php: fixes access to uninitialized array elements.
Download.php: get dbT3 now from STORE_SYSTEM
Config.php: read 'dbNameT3' from TYPO3_CONF_VARS or from T3 config file.
QuickFormQuery.php: refactor gathering 'dbNames' - now from config.qfq.php. Fixes bug in getForwardMode() for QFQ inline editing.

Fixes #7001 - Error message: if 'modeSql' fails, error message does not contain a reference to the causing FE.

AbstractException.php: fixed problem with htmlEntities() on link to 'Edit Form' and 'Edit FormElement'.

F5458 Error Log Unique Identifier: Exception message might be an ordinary string or a JSON encoded array.

#5367 / Error Report: 'full level' missing: still miss when UserReport Exceptions are thrown - fixed

#5367 / Error Report: 'full level' missing: still miss when UserReport Exceptions are thrown - fixed

#5367 / Error Report: 'full level' missing, content too much escaped: Fixed too much escaping. Form / FormElement Links in error messages now with BS Buttons.