- fixed issue when exporting DXF and not settings the units

- added the posibility to export the Geometry in different DXF formats (previously it was hard coded to the AutoCAD 2010): R12, R2000, R2004, R2007, R2010, R2013, R2018
- fixed the camlib.Geometry.bounds() method such that it is calculated correctly for Geometry objects created in the Geometry Editor

defaults.py

@@ -304,6 +304,9 @@ class FlatCAMDefaults:
         "geometry_segx": 0.0,
         "geometry_segy": 0.0,
 
+        # Geometry Export
+        "geometry_dxf_format": 'R2010',
+
         # Geometry Options
         "tools_mill_tooldia": "2.4",
         "tools_mill_offset_type": 0,    # _('Path')