Make ScrollMenu not rely on Menu.cpp

Rename ScrollMenu.cpp to MenuScrollView.cpp

Half step towards making this class work as part of Deskbar without
extending any other classes. Scrolling works both with mouse and
scroll wheel. Redraws on scroll, need to make that work better.
Also need to move classes out of the Interface Kit and into Deskbar.

src/kits/interface/MenuBar.cpp

@@ -18,7 +18,7 @@
 #include <ControlLook.h>
 #include <LayoutUtils.h>
 #include <MenuItem.h>
-#include <ScrollMenu.h>
+#include <MenuScrollView.h>
 #include <Window.h>
 
 #include <AppMisc.h>
@@ -329,36 +329,7 @@ BMenuBar::Draw(BRect updateRect)
 void
 BMenuBar::MessageReceived(BMessage* msg)
 {
-	switch (msg->what) {
-		case B_MOUSE_WHEEL_CHANGED:
-		{
-			float deltaY = 0;
-			msg->FindFloat("be:wheel_delta_y", &deltaY);
-			if (deltaY == 0)
-				return;
-
-			BScrollMenu* scrollMenu = dynamic_cast<BScrollMenu*>(Parent());
-			if (scrollMenu == NULL)
-				return;
-
-			float largeStep;
-			float smallStep;
-			scrollMenu->GetSteps(&smallStep, &largeStep);
-
-			// pressing the option/command/control key scrolls faster
-			if (modifiers() & (B_OPTION_KEY | B_COMMAND_KEY | B_CONTROL_KEY))
-				deltaY *= largeStep;
-			else
-				deltaY *= smallStep;
-
-			scrollMenu->TryScrollBy(deltaY);
-			break;
-		}
-
-		default:
-			BMenu::MessageReceived(msg);
-			break;
-	}
+	BMenu::MessageReceived(msg);
 }