SAMD CORE 1.6.6

* Fixed digitalPinToInterrupt() macro, now it works as documented.
* Added analogInputToDigitalPin macro
* Fixed NUM_DIGITAL_PINS for Zero Board.
* On-board RX-TX LEDs now blinks when there is activity on the native USB port
* Fixed platform.txt, the core now compiles again with Arduino IDE <=1.6.5. Thanks @per1234
* Fixed Wire.write(0x00) "ambiguos method" error
* String class now supports iterators. Thanks @Chris--A
* Remove enabling bootloader protection when burning bootloader. This enables WDT, so sketches do not work.

SAMD CORE 1.6.5 2016.04.02

* Added Arduino/Genuino MKR1000 board
* Set NVMCTRL.MANW bit to 1 (default is 0). This prevents accidental writes on program memory.
* Bootloader: Fixed wrong UART speed (regression)
* Fixed incorrect return value from Wire.available() when the receive buffer is not fully read.
* Added DAC0 definition in Arduino/Genuino Zero variant file.
* Enabled bootloader protection after "Burn bootloader".

SAMD CORE 1.6.4 2016.02.19

* Fixed Wire address setup when running as slave.
* Fixed String constructor when using floating point numbers.
* USBHost: fixed blocking USBHost.Task(). Thanks @bbx10
* USBHost: fixed some ASCII Control codes in keyboard controller. Thanks @bbx10
* USBHost: ported some minor fix from upstream UHS2. Thanks @bbx10
* USBHost: fixed wrong library initialization. Thanks @bbx10 @ladyada
* better interrupt handling in Serial::accept()

SAMD CORE 1.6.3 2016.02.15

* Added drivers for Arduino/Genuino MKR1000 board
* Fixed Wire master repeated start behaviour
* Added SerialUSB methods: readBreak(), baud(), stopbits(), paritytype(), numbits(), dtr(), rts()
* Added SPI.transfer16(..) method
* Bugfix: added missing Serial.begin(baud, config) method. Thanks @tuxedo0801
* Fixed Serial baudrate calculations for 1200bps. Thanks @TomKeddie
* Fixed Serial.flush() that now waits until the last bit has been sent. Thanks @TomKeddie
* Fixed Serial configuration for data-bit. Thanks @TomKeddie
* Bootloader: 32Khz external oscillator is now used, improves USB clock. Thanks @aethaniel
* Bootloader: Clean up of makefiles and file organization. Thanks @aethaniel
* Added PWM capability to pins A1/A2 of Arduino Zero.
* variant.h/cpp: PWM capability is now determined by PIN_ATTR_PWM combined with
                 PIN_ATTR_TIMER or PIN_ATTR_TIMER_ALT for timer selection.
* Small fix to USBHost example "USB_desc.ino". Thanks @bbx10
* USBHost: USB-Keyboard right shift key was ignored. Thanks @bbx10 
* Wire library now support multiple instances in variant. Thanks @spiderkeys
* Ported some SerialUSB API (readBreak(), baud(), stopbits(), paritytype(), numbits(), dtr(), rts())

SAMD CORE 1.6.2 2015.11.03

* Fixed bug in delay calculations
* Fixed deadlock conditions in Wire. Thanks Erin Tomson
* Print not aborting on write() failure. Thanks @stickbreaker
* SPI can now be configured in variants. Thanks @aethaniel
* Implemented Wire.end
* Fixed external interrupt for pin 8 and 9
* Implemented Wire.setClock. Thanks @PaoloP74
* Wire: allow scanning bus via beginTransmission-endTransmission
* USB Device: big refactoring and bug fix
* USB Device: added PluggableUSB interface
* updated bossac to version 1.6.1-arduino

SAMD CORE 1.6.1 2015.07.21

* Added missing ATN pin definition
* Added missing bootloader key/value pair in boards.txt (this allows to burn bootloader with Sam-ICE too)
* Fixed min/max functions
* Fixed hooks for Cortex-M RTOS
* Fixed acknowledge of UART errors
* Enabled C11/C++11
* Fixed initialization in USB Device
* Updated bossac to version 1.6-arduino

SAMD CORE 1.6.0  2015.06.15

* First public release.

