Merge X11+D3D FreeLook feature into DolphinWX

This removes the redundant code and also implements this feature for OSX and Wayland.
But so it's dropped for non-wx builds...

imo DolphinWX still isn't the best place for this, but now it's in the same file as all other hotkeys. Maybe they'll be moved to InputCommon sometimes at once ...

Source/Core/DolphinWX/Src/Frame.cpp

@@ -1028,6 +1028,59 @@ void CFrame::OnMouse(wxMouseEvent& event)
 					event.GetPosition().x, event.GetPosition().y, event.ButtonDown());
 	}
 #endif
+
+	// next handlers are all for FreeLook, so we don't need to check them if disabled
+	if(!g_Config.bFreeLook)
+	{
+		event.Skip();
+		return;
+	}
+
+	// Free look variables
+	static bool mouseLookEnabled = false;
+	static bool mouseMoveEnabled = false;
+	static float lastMouse[2];
+
+	if(event.MiddleDown())
+	{
+		lastMouse[0] = event.GetX();
+		lastMouse[1] = event.GetY();
+		mouseMoveEnabled = true;
+	}
+	else if(event.RightDown())
+	{
+		lastMouse[0] = event.GetX();
+		lastMouse[1] = event.GetY();
+		mouseLookEnabled = true;
+	}
+	else if(event.MiddleUp())
+	{
+		mouseMoveEnabled = false;
+	}
+	else if(event.RightUp())
+	{
+		mouseLookEnabled = false;
+	}
+	// no button, so it's a move event
+	else if(event.GetButton() == wxMOUSE_BTN_NONE)
+	{
+		if (mouseLookEnabled)
+		{
+			VertexShaderManager::RotateView((event.GetX() - lastMouse[0]) / 200.0f,
+					(event.GetY() - lastMouse[1]) / 200.0f);
+			lastMouse[0] = event.GetX();
+			lastMouse[1] = event.GetY();
+		}
+
+		if (mouseMoveEnabled)
+		{
+			VertexShaderManager::TranslateView((event.GetX() - lastMouse[0]) / 50.0f,
+					(event.GetY() - lastMouse[1]) / 50.0f);
+			lastMouse[0] = event.GetX();
+			lastMouse[1] = event.GetY();
+		}
+	}
+
 	event.Skip();
 }