- more PEP8 changes

- in PreferencesUI.PreferencesUIManager class I removed the need to pass reference to the App class since it this was available through the 'ui' parameter
- some fixes due to recent refactoring
- minor bugs fixed (not so visible)
- promoted some methods to be static
- set the default layout on first run to the 'minimal' value

flatcamGUI/FlatCAMGUI.py

@@ -2573,9 +2573,9 @@ class FlatCAMGUI(QtWidgets.QMainWindow):
         self.run_script_btn = self.toolbarshell.addAction(
             QtGui.QIcon(self.app.resource_location + '/script16.png'), _('Run Script ...'))
 
-        # ########################################################################
-        # ## Tools Toolbar # ##
-        # ########################################################################
+        # #########################################################################
+        # ######################### Tools Toolbar #################################
+        # #########################################################################
         self.dblsided_btn = self.toolbartools.addAction(
             QtGui.QIcon(self.app.resource_location + '/doubleside32.png'), _("2Sided Tool"))
         self.align_btn = self.toolbartools.addAction(
@@ -2619,6 +2619,10 @@ class FlatCAMGUI(QtWidgets.QMainWindow):
             QtGui.QIcon(self.app.resource_location + '/fiducials_32.png'), _("Fiducials Tool"))
         self.cal_btn = self.toolbartools.addAction(
             QtGui.QIcon(self.app.resource_location + '/calibrate_32.png'), _("Calibration Tool"))
+        self.punch_btn = self.toolbartools.addAction(
+            QtGui.QIcon(self.app.resource_location + '/punch32.png'), _("Punch Gerber Tool"))
+        self.invert_btn = self.toolbartools.addAction(
+            QtGui.QIcon(self.app.resource_location + '/invert32.png'), _("Invert Gerber Tool"))
 
         # ########################################################################
         # ## Excellon Editor Toolbar # ##