Add option to place extension menu items at top.
Add option to place extension menu items at top.

This addresses #15, though this functionality could be implemented in a
few different ways and is worth discussing.

EvNaverniouk/doby-grid,RobertoMalatesta/doby-grid,RobertoMalatesta/doby-grid,globexdesigns/doby-grid,EvNaverniouk/doby-grid,globexdesigns/doby-grid