[MapEditor] Hiding empty directories from the listing
[MapEditor] Improved directory scanning

Scanning is now processed in a swing worker thread. This speeds up the
GUI. Furthermore a bug was fixed that caused the event bus to crash in
case no entry is listed in the file listing.
[MapEditor] Scan directory in background thread

The directories are now scanned for maps in a background thread that
does not freeze up the GUI.
[Nifty-Controls] Showing and hiding craft item counter properly

The counter that show how many items are created is now properly shown
in case the value is greater then one.
[Client] Cleanup trading commands
[Client] Implementation of the trading lookat network command
[Client] Ensure that the minimap arrows are deleted during the next update
[Client] Improve selection dialog

The dialog now optimizes the amount of entries displayed.
Also there is now the possibility to confirm a selection with a click on
a button and the selection does actually work.
[Client] Improve selection dialog

The dialog now sets its width according to the width of its entries.
Could cause problems with very long description texts.
[Client] Fix multiple quest markers at one location

The client is now filtering quest markers that are assigned to the same location.
Those questmarkers are not displayed anymore.
[Client] Dialog creation by execution service

The dialogs are now prepared by the execution service in
tasks that are executed parallel as needed. The dedicated
update queue of the dialog handler was replaced by the global
update queue.