remove ui namespace which is not really used, move CameraData in camera_modes.h to avoid the inclusion of canva.h

src/app_commands.cpp

@@ -9,7 +9,7 @@ void App::cmd_convert(std::string pano_path, std::string out_path)
     glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
     glBlendEquation(GL_FUNC_ADD);
 
-    ui::Canvas* canvas = new ui::Canvas;
+    Canvas* canvas = new Canvas;
     canvas->create(CANVAS_RES, CANVAS_RES);
     canvas->project_open_thread(pano_path);
     canvas->export_equirectangular_thread(out_path);