u02/tool_base: Add draw with no point

u02/include/tool_base.h

@@ -35,6 +35,8 @@ public:
   // Initialize the tool and store a reference of a canvas_buffer
   tool_base(canvas_buffer &canvas);
 
+  // Draw with no point provided
+  virtual void draw();
   // Draw with one point provided
   virtual void draw(int x, int y);
   // Draw with two points provided

u02/src/tool_base.cpp

@@ -11,6 +11,12 @@ tool_base::tool_base(canvas_buffer &canvas) : canvas(canvas) {
   is_draggable = true;
 }
 
+// Draw with no point provided
+void tool_base::draw() {
+  // Nothing implemented here. Children of this class can implement
+  // this method if needed
+}
+
 // Draw with one point provided
 void tool_base::draw(int x, int y) {
   // Nothing implemented here. Children of this class can implement