Python binding: fix pcbnew.Refresh() to make a better re-initialization.

Minor fixes in comments.

Fixes: lp:1775003
https://bugs.launchpad.net/kicad/+bug/1775003

pcbnew/swig/pcbnew_scripting_helpers.cpp

@@ -110,9 +110,11 @@ void Refresh()
 
         if( s_PcbEditFrame->IsGalCanvasActive() )
         {
-            auto panel = static_cast<PCB_DRAW_PANEL_GAL*>( s_PcbEditFrame->GetGalCanvas() );
-            panel->DisplayBoard(board);
-            s_PcbEditFrame->GetGalCanvas()->Refresh();
+            auto gal_canvas = static_cast<PCB_DRAW_PANEL_GAL*>( s_PcbEditFrame->GetGalCanvas() );
+
+            // Reinit everything: this is the easy way to do that
+            s_PcbEditFrame->UseGalCanvas( true );
+            gal_canvas->Refresh();
         }
         else
             // first argument is erase background, second is a wxRect that

pcbnew/swig/pcbnew_scripting_helpers.h

@@ -50,7 +50,7 @@ BOARD*  LoadBoard( wxString& aFileName );
 bool    SaveBoard( wxString& aFileName, BOARD* aBoard );
 
 /**
- * Update the board display after modifying it bu a python script
+ * Update the board display after modifying it by a python script
  * (note: it is automatically called by action plugins, after running the plugin,
  * so call this function is usually not needed inside action plugins
  *

utils/kicad2step/pcb/oce_utils.cpp

@@ -82,7 +82,7 @@
 // nominal offset from the board
 #define BOARD_OFFSET (0.05 )
 // min. length**2 below which 2 points are considered coincident
-#define MIN_LENGTH2 (0.0001)
+#define MIN_LENGTH2 (0.0001)    // = 0.01*0.01
 
 static void getEndPoints( const KICADCURVE& aCurve, double& spx0, double& spy0,
     double& epx0, double& epy0 )