Borrow some functions from arduino.mk to show all build options.
Borrow some functions from arduino.mk to show all build options.

Fixed #191.

openxc/vi-firmware,mgiannikouris/vi-firmware,ene-ilies/vi-firmware,ene-ilies/vi-firmware,ene-ilies/vi-firmware,mgiannikouris/vi-firmware,mgiannikouris/vi-firmware,openxc/vi-firmware,openxc/vi-firmware,openxc/vi-firmware,ene-ilies/vi-firmware,mgiannikouris/vi-firmware