[BoxCreator] Create a new document if necessary

- Create a new document if necessary.
- Make some functions "private".
- Fix some whitespace.
- Deduce the document from argument `box` in `create_compartment`.

Author: galou

ObjectCreation/BoxCreator.FCMacro

@@ -3,10 +3,10 @@
 __Name__ = 'BoxCreator'
 __Comment__ = 'Creates a box with interlocked notches'
 __Author__ = 'christi'
-__Version__ = '1.3.2'
-__Date__ = '2020-02-08'
+__Version__ = '1.3.3'
+__Date__ = '2020-03-10'
 __License__ = 'LGPL-3.0-or-later'
-__Web__ = 'https://github.com/chbergmann/boxcreator'
+__Web__ = 'https://forum.freecadweb.org/viewtopic.php?t=31795'
 __Wiki__ = ''
 __Icon__ = ''
 __Help__ = 'Try it out and play with it. It should be self explanatory'
@@ -20,7 +20,7 @@ import os
 
 import FreeCAD as app
 import FreeCADGui as gui
-from PySide import QtGui
+from PySide import QtGui  # Special FreeCAD's PySide.
 from FreeCAD import Vector
 
 from boxcreator import boxcreator
@@ -73,6 +73,8 @@ class BoxcreatorDialog():
         gui.Selection.clearSelection()
         gui.Selection.addSelection(box)
         gui.SendMsgToActiveView('ViewFit')
+        del self.widget
+        del self.form
 
     def compartmentX(self):
         self.createCompartment(Vector(1,0,0))
@@ -95,7 +97,7 @@ class BoxcreatorDialog():
                      self.form.checkBoxBack.isChecked()]
         offset = self.form.compartmentOffset.value()
         boxsize = Vector(self.form.doubleSpinBoxWidth.value(), self.form.doubleSpinBoxLength.value(), self.form.doubleSpinBoxHeight.value())
-        compartment = boxcreator.create_compartment(box, direction, offset, materialWidth, notchWidth, drawSides, boxsize, app.activeDocument())
+        compartment = boxcreator.create_compartment(box, direction, offset, materialWidth, notchWidth, drawSides, boxsize)
         if compartment:
             gui.Selection.clearSelection()
             gui.Selection.addSelection(compartment)