Added setValue and setValues method.
Fixes unterminated string literal problem.
Implements dateDiff modifier

Example: `{122331660|dateDiff:0:true}` results in `3 years, 10 months, 2 weeks, a day, 21 hours and a minute ago`, while `{122331660|dateDiff:0}` results in `3 years ago`.
Updates code in regard of internal changes within the previous commit
Adds several interfaces for dbo actions

Please be aware that the API for searching objects via AJAX changed!
Implements now IDatabaseObjectProcessor.
fix icon change
Indroduced _setOption in wcfDialog-widget
Removed debug line
Added overlayLoading-style
Fixed rendering
Merge branch 'master' of github.com:WoltLab/WCF into feature/wcfDialog/_setOption
Sets default i18n lang var category for categories
Enhances package installation plugins

Changes:

* Adds `DatabaseObjectDecorator::getDatabaseTableAlias()` (needed later)
* Removes obsolete `PageLocationPackageInstallationPlugin`
* `AbstractXMLPackageInstallationPlugin::$tableName` is automatically set if it is empty and `AbstractXMLPackageInstallationPlugin::$className` is set.
* `AbstractXMLPackageInstallationPlugin::$tagName ` is automatically set if it is empty and `AbstractXMLPackageInstallationPlugin::$tableName` is set/has been automatically set.
* Updates/Adds some comments
* Removes obsolete `ACPTemplatePackageInstallationPlugin::$tagName`
* Fixes #769
Reverts changing position of abstract keyword
Implements User::getLanguageIDs() for guests
Fixes error
Enhances names of acp search result providers

Additional, the language items for the searched object types are added.
Fixes schema locations
Merge pull request #11 from Gravatronics/bug/schemaLocations

Fixes schema locations