Circular and pie-slice menu

This version provides services for creating menu:

• with circular shaped items (sub-menus are created around their item) [available from v0.1]
• with pie-slice shaped items (sub-menus are created as circular rings around the menu) [new feature]
  

Initial version

This is the initial version of this contextual graphic menu contains:

• radial layout of the items with a central item
• empty or circular shaped background for main and sub menus
• circular items (made of background and a label)
• submenus open around their item

Coming soon (more or less):

• icons on the items
• other background shapes
• other opening behaviors