Refactoring: zones and keepout areas are drawn using the same function.

pcbnew/tools/drawing_tool.h

@@ -75,9 +75,14 @@ public:
     int PlaceModule( TOOL_EVENT& aEvent );
 
 private:
-    ///> Starts drawing a selected shape.
+    ///> Starts drawing a selected shape (i.e. DRAWSEGMENT).
+    ///> @param aShape is the type of created shape (@see STROKE_T).
     int draw( int aShape );
 
+    ///> Draws a polygon, that is added as a zone or a keepout area.
+    ///> @param aKeepout decides if the drawn polygon is a zone or a keepout area.
+    int drawZone( bool aKeepout );
+
     ///> Sets up handlers for various events.
     void setTransitions();