ENH: Fix call signature to save/load clip-planes.
ENH: Fix call signature to save/load clip-planes.

Error code:
```bash
Traceback (most recent call last):
  File "/path/Software/Slicer/Extensions/EasyClip-Extension/build/lib/Slicer-4.9/qt-scripted-modules/EasyClip.py", line 215, in savePlane
    self.logic.saveFunction()
  File "/path/Software/Slicer/Extensions/EasyClip-Extension/build/lib/Slicer-4.9/qt-scripted-modules/EasyClip.py", line 521, in saveFunction
    filename = qt.QFileDialog.getSaveFileName(parent=self,caption='Save file')
```

JuliaLopinto/EasyClip-Extension,DCBIA-OrthoLab/EasyClip-Extension