Use AIFilePicker everywhere.

Also upgrade the file picker filters with the new extensions found
in the orginal file picker code of Singularity.

Also improve AIFilePicker a bit: added hasFilename() and now
deleting the statemachine automatically by default: it's no longer
needed to call deleteMe from the callback.

indra/newview/llviewerobjectbackup.h

@@ -56,9 +56,11 @@ public:
 
 	// Import entry point
 	void importObject(bool upload=FALSE);
+	void importObject_continued(AIFilePicker* filepicker);
 
 	// Export entry point
 	void exportObject();
+	void exportObject_continued(AIFilePicker* filepicker);
 
 	// Update map from texture worker
 	void updateMap(LLUUID uploaded_asset);