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

src/node_stroke_preview.h

@@ -9,10 +9,10 @@ class NodeStrokePreview : public NodeBorder
     RTT m_rtt;
     Sampler m_sampler;
     Sampler m_sampler_brush;
-    ui::BrushMesh m_mesh;
+    BrushMesh m_mesh;
 public:
-    ui::Brush m_brush;
-    ui::Stroke m_stroke;
+    Brush m_brush;
+    Stroke m_stroke;
     std::vector<glm::vec2> m_bez_points;
     virtual Node* clone_instantiate() const override;
     virtual void clone_copy(Node* dest) const override;