- 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

appObjects/FlatCAMGeometry.py

@@ -1963,10 +1963,16 @@ class GeometryObject(FlatCAMObj, Geometry):
 
     def export_dxf(self):
         dwg = None
+        dxf_format = self.app.defaults['geometry_dxf_format']
+
         try:
-            dwg = ezdxf.new('R2010')
+            dwg = ezdxf.new(dxf_format)
             msp = dwg.modelspace()
 
+            # add units
+            dwg.units = ezdxf.InsertUnits(4) if self.app.defaults['units'].lower() == 'mm' else ezdxf.InsertUnits(1)
+            dwg.header['$MEASUREMENT'] = 1 if self.app.defaults['units'].lower() == 'mm' else 0
+
             def g2dxf(dxf_space, geo_obj):
                 if isinstance(geo_obj, MultiPolygon):
                     for poly in geo_obj: