Make a little change to the EmptyTableHandler API

Additionally, the default message type is info instead of warning.
Merge pull request #542 from Gravatronics/enhancement/EmptyTableHandler/APIChange

Make a little change to the EmptyTableHandler API
Adds the possibility to auto-trigger action effects in WCF.Clipboard

If a clipboard item has the following parameters:

* actionName
* className
* objectIDs (ids of the marked objects which would be affected by the action)

the following things happen:

* An AJAX action with actionName and className is executed (if additionally a confirm message is given, the user has to handle that first before the action is executed).
* It's checked if an action object for the relevant object type and actionName exists in WCF.Clipboard exists and for each object id in objectIDs triggerEffect(objectID) on the action object is called. This way deleted objects are also removed from the table or toggled objects get updated toggle "buttons".

To achieve the second part, WCF.Action.Delete and WCF.Action.Toggle have a new method: triggerEffect() which is basically the content of _success but can now be called from WCF.Clipboard with the relevant object ids.
Furthermore UserClipboardAction returns the relevant user ids if the delete action is active.

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Additionally, I update the javascript handling of the user list in the acp:

* The deletion button works and uses WCF.Action.Delete.
* The new WCF.Table.EmptyTablerHandler is in use.
* The above mentioned WCF.Clipboard changed are implemented which is mainly adding a few javascript lines and removing several obsolete lines from WCF.ACP.
Fixes ClipboardActionPackageInstallationPlugin

Previously, an actionName has to be unique within a package, now the combination of actionName and actionClassName has to be unique within a package.

Without this fix, you can't install two actions named "delete" within one file - even if they are for a completely different actionClass and page(s).
Merge pull request #544 from Gravatronics/bug/clipboard/PIPFix

Fixes ClipboardActionPackageInstallationPlugin
Merge pull request #543 from Gravatronics/enhancement/clipboard/autoEffectTriggering

Adds the possibility to auto-trigger action effects in WCF.Clipboard
Fixes return value of UserEditor::deleteAll()
Fixes DatabaseObjectEditor::deleteAll() return value

This way the number of deleted objects is returned and not the number of given object ids.
Merge pull request #548 from Gravatronics/bug/userEditorDeleteAllReturnValue

Fixes return value of UserEditor::deleteAll()
Merge pull request #549 from Gravatronics/bug/deleteAllReurnValue

Fixes DatabaseObjectEditor::deleteAll() return value
Added language export function
Merge pull request #551 from Siora/patch-4

Added language export function
Reworked templates, added LESS-based stylesheets
Updated template plugins to match new structure
Use a static CSS for WCFSetup

Will be replaced later by a reduced, static version of WCF-ACP LESS-Stylesheets. Due to major laziness I will just use the old wcf.css even though it contains way too much stuff.
Fixed tooltips
More template/css fixes
Fixed sortables
More template fixes
Merge branch 'master' of github.com:WoltLab/WCF