- some changes in the app.on_togle_units() to make sure we don't try to convert empty parameters which may cause crashes on FlatCAM units change

- updated setup_ubuntu.sh file
- made sure to import certain libraries in some of the FlatCAM files and not to rely on chained imports

flatcamTools/ToolCutOut.py

@@ -2,6 +2,7 @@ from FlatCAMTool import FlatCAMTool
 from ObjectCollection import *
 from FlatCAMApp import *
 from shapely.geometry import box
+from shapely.ops import cascaded_union, unary_union
 
 import gettext
 import FlatCAMTranslation as fcTranslate