Copter: add pre-arm board voltage check

Copter will not arm unless board voltage is over 4.5V
OptFlow: minor commenting and format changes
autotest: start copter pointing south

useful for testing compass errors
Rover: fixed logging of sonar distance
autotest: tweaks to rover autotest for sparkfun
autotest: added CopterAVC test

this will test the copter code for the AVC2013 mission
autotest: tweak AVC copter mission
Copter: added support for partial mission load

this allows individual waypoints to be updated in missions
autotest: add sparkfun wicket icons on map
Copter: fixed loading of waypoints

copter code assumes that command_total includes the home waypoint
Plane: added BATT_MONITOR and VOLT_DIVIDER docs
Plane: added more parameter docs (flaps and GCS control)
RC_Channel: fixed indent-tabs-mode
PID: fixed indent-tabs-mode
GCS_MAVLink: fixed indent-tabs-mode
AP_RangeFinder: fixed indent-tabs-mode
AP_Mount: fixed indent-tabs-mode
AP_Motors: fixed indent-tabs-mode
AP_Menu: fixed indent-tabs-mode
AP_Math: fixed indent-tabs-mode