Pie menu (chapter)

Need add some info (as chapter) about "pie menu", that came since OpenOrienteering Mapper v0.4, and how it work/look in different situations.

• http://www.openorienteering.org/news/2012/openorienteering-mapper-0-4-provides-a-wealth-of-new-features
  ...
  Editing tools
• Right-click pie menu for quick tool switching without keyboard shortcuts
  
  The ring-shaped context menu allows for quick access to tools.

REFERENCES

• https://medium.com/@donhopkins/pie-menus-936fed383ff1
  • https://news.ycombinator.com/item?id=17098179