Copter: slow motors after landing in AUTO

This resolves an issue in which the vehicle could tip over if the pilot
did not reduce the throttle to zero soon after landing in AUTO mode
Copter: set home alt to absolute alt
Copter: remove home variable

home has moved to ahrs
saves 15 bytes of RAM
Copter: bug fix to remove home variable

pair programmed with Craig Elder
VRBRAIN: Changed the management of VirtualRobotix's boards.
VRBRAIN: Changed the management of VirtualRobotix's boards.
Added missing files
VRBRAIN: Scripts for VRBRAIB custom start
VRBRAIN: Added makefile and startup scripts for VR Brain 5 board.
VRBRAIN: added missing boards definition
VRBRAIN: added VRBRAIN to #if
VRBRAIN: correction to AP_Compass_VRBRAIN.cpp