Cut: Hide Debug window, leave rectangle mode for the cut plane

+ Fixed CameraUtils::ray_from_persp_screen_pos() to return a correct value of the point

src/slic3r/GUI/Gizmos/GLGizmoCut.cpp

@@ -1426,6 +1426,7 @@ void GLGizmoCut3D::on_render()
 
 void GLGizmoCut3D::render_debug_input_window(float x)
 {
+    return;
     m_imgui->begin(wxString("DEBUG"));
 
     ImVec2 pos = ImGui::GetWindowPos();