Patch for Path and Poligon handlers.
Extends `Path` & `Polygon` handlers to remove the last added point or delete the drawing if no more points to remove by esc-key. The keys act only when the cursor is on the map.
NOTE: At the build process “requires” for Polygon.js is not strictly necessary, so if not want to use Handler.Polygon the Polygon.js file could be added in [exclude] paragraph in the *.cfg file.