ResourceItem: added descriptiveTypeName() method

The new ResourceItem::descriptiveTypeName() allows to query a
descriptive name for a given ResourceItem type.

include/ResourceItem.h

@@ -231,6 +231,8 @@ public:
 	static QString getBaseDirectory( BaseDirectory _bd,
 					const ResourceItem * _item = NULL );
 
+	static QString descriptiveTypeName( Type _type );
+
 
 private:
 	void init();