Add AIDirPicker and use it. Remove indra/newview/ll{dir,file}picker.{h,cpp}.

Also removed some code from the Mac/windows code in
indra/plugins/filepicker/llfilepicker.cpp that shouldn't
be in there anymore (send_agent_pause/resume and updating
the LLFrameTimer stuff).

indra/newview/llinventorybackup.h

@@ -15,6 +15,8 @@
 #include "llviewertexture.h"
 #include "llfloater.h"
 
+class AIDirPicker;
+
 class LLInventoryBackupOrder
 {
 public:
@@ -44,6 +46,7 @@ public:
 	LLFloaterInventoryBackupSettings(LLInventoryBackupOrder* order);
 	BOOL postBuild(void);
 	static void onClickNext(void* userdata);
+	static void onClickNext_continued(void* userdata, AIDirPicker* dirpicker);
 
 	LLInventoryBackupOrder* mOrder;
 	virtual ~LLFloaterInventoryBackupSettings();