Add mark point button getter

Author: Manuel Manso

pythonvideoannotator_models_gui/models/video/objects/object2d/datasets/path/path_gui.py

@@ -347,6 +347,10 @@ def parent_treenode(self):  return self._object2d.treenode
     @property
     def interpolation_mode(self): return None if self._interpolation_mode.value==-1 else self._interpolation_mode.value
 
+    @property
+    def mark_point_button(self):
+        return self._mark_pto_btn
+
 
     @property
     def referencial(self):