- refactored the imports in the Plugins, moved almost all imports in the AppTool file

- fixed a number of issues, mostly leftovers from moving the UI of a Plugin in its own class
- fixed some bugs in the Punch Gerber plugin
- fixed some bugs where the 'pool' parameter was not passed when creating shapes collections (in 3D graphic mode); I wonder how it worked until now
- added a new feature in the Isolation Plugin: now for all the isolation Geometry objects this plugin can do a supplementary simplification of the geometry using the tolerance parameter defined in the General Parameters. This should lead to a reduced number of tool lifts when doing corners

defaults.py

@@ -390,6 +390,8 @@ class AppDefaults:
         "tools_iso_poly_ints":      False,
         "tools_iso_force":          True,
         "tools_iso_area_shape":     "square",
+        "tools_iso_simplification":     False,
+        "tools_iso_simplification_tol": 0.01,
         "tools_iso_plotting":       'normal',
 
         # Drilling Plugin