- made possible to set the colors for Excellon objects too

- added to the possible colors the fundamentals: black and white
- in the project context menu for setting colors added the option to set the transparency and also a default option which revert the color to the default value set in the Preferences

ObjectCollection.py

@@ -338,7 +338,7 @@ class ObjectCollection(QtCore.QAbstractItemModel):
             self.app.ui.menuprojectcolor.setEnabled(False)
 
             for obj in self.get_selected():
-                if type(obj) == FlatCAMGerber:
+                if type(obj) == FlatCAMGerber or type(obj) == FlatCAMExcellon:
                     self.app.ui.menuprojectcolor.setEnabled(True)
 
                 if type(obj) != FlatCAMGeometry: