slow down input a bit in setup mode

this is friendier for the PX4 serial console, preventing loss of bytes
due to interrupt storms
mavflightview: support PX4 native SD log format
widgets: added menu controls 

this will allow for menus on all windows
menu: moved mp_menu to lib and create a proper class hierarchy
mp_menu: support radio button menus
mp_menu: allow default selection in radio button menus
map: switched to menu driven choices
map: removed unused File menu
mp_image: don't clog pipes to dead children
mp_menu: added popup menus
mp_image: added popup menus in mp_image
mp_image: removed debug line
map: show grid by default
mp_util: support grids in northern hemisphere
menu: allow initially checked menu items
mp_util: added PIL <-> wx image conversion functions
mp_image: added brightness controls
mp_image: support full_size() and fit_to_window()
mp_menu: fixed menus on windows
slipmap: put grid on bottom layer