Merge branch 'zero' of github.com:aethaniel/ArduinoZero into zero

cores/arduino/HOWTO_compiling_a_project_with_GCC.txt

cores/arduino/delay.c

cores/arduino/delay.h

cores/arduino/main.cpp

cores/arduino/startup.c

cores/arduino/validation/build_as6/test.atsuo

cores/arduino/validation/build_as6/test.cppproj

cores/arduino/validation/test.cpp

cores/arduino/wiring.c

cores/arduino/wiring_digital.c

variants/arduino_zero/debug_scripts/variant.gdb

variants/arduino_zero/variant.cpp