AP_Menu: dynamically allocate the menu buffers

this saves memory when the menus are not used, and allows for the
commandline and argument limits to be changed
AP_Menu: zero buffer contents on allocation
AP_Menu: added check_for_input() API

this allows for async use of the menus, so that a main loop can run
while allowing the user to enter menu commands
ArduKTH: this is an import from KTH

ArduKTH is a schools project run by Jakob Kuttenkeuler
ArduKTH: Jakob added a misspelled comment

bla bla
ArduKTH: Reduced mem usage to fix reboot problem.
ArduKTH: More RAM memory with smarter printing :-)
ArduKTH: hack to allow SITL to work with no parameters
ArduKTH: changed logging to start a new log on each new mission start
ArduKTH: implement PSTR() for all printf() calls
ArduKTH: added PSTR() to all println calls
ArduKTH: General cleanup.
ArduKTH: Cleanup
ArduKTH: More cleanup
ArduKTH: Switched to AP_menu

The commit is not running properly...
ArduKTH: fixes for changes to APIs in master

fixes after rebase
ArduKTH: use larger menu limits
ArduKTH: use new check_for_input() in AP_Menu

and remove the "is alive" message :-)