Add MKRFox1200 support to SDU (and rebuild for all boards)

This enables remote wakeup on CDC driver, so we can safely call standby() and maintain the Serial prints on resume.

Correct OpenOCD version in tools.openocd.path definition

http://downloads.arduino.cc/packages/package_index.json specifies
openocd version 0.9.0-arduino6-static in the Arduino SAMD Boards 1.6.13
entry. The incorrect version previously used to define
tools.openocd.path caused uploads for SAMD boards to fail:
"java.io.IOException: Cannot run program
"{runtime.tools.openocd-0.9.0-arduino5-static.path}/bin/openocd.exe":
CreateProcess error=2, The system cannot find the file specified"

Add SDU usage example

Add support for updating sketches from an SD card

Fix #216

CMSIS-Atmel 4.5 changed the prescaler defines to match the bit mask, not the actual prescaler value, thus `SYSCTRL_OSC8M_PRESC_1_Val`  now means "divide by 2"

Fixes https://github.com/arduino/ArduinoCore-samd/issues/214

Via 2nd stage boot code that checks SD card for UPDATE.bin

Add virtual beginMulticast(...) stub to UDP class

https://github.com/arduino/ArduinoCore-samd/commit/5b7c293b2f9c86d1ef75708ba0ebc2755e5bd39b changed the dependency from CMSIS-Atmel 1.0.0 to 1.1.0

upd: optimization openocd version control

upd: optimization of openocd (mips) installation procedure

    * cores/arduino/wiring.c:

This reverts commit b04ddad1.

Set full PINCFG register on pinMode(pin, OUTPUT)

Fix #206