Updated bundled AVR core to 1.6.19

Author: cmaglie

platform.txt

@@ -6,7 +6,7 @@
 # https://github.com/arduino/Arduino/wiki/Arduino-IDE-1.5-3rd-party-Hardware-specification
 
 name=Arduino AVR Boards
-version=1.6.18
+version=1.6.19
 
 # AVR compile variables
 # ---------------------
@@ -127,4 +127,4 @@ tools.avrdude.upload.network_pattern="{network_cmd}" -address {serial.port} -por
 # Default blank usb manufacturer will be filled in at compile time
 # - from numeric vendor ID, set to Unknown otherwise
 build.usb_manufacturer="Unknown"
-build.usb_flags=-DUSB_VID={build.vid} -DUSB_PID={build.pid} '-DUSB_MANUFACTURER={build.usb_manufacturer}' '-DUSB_PRODUCT={build.usb_product}'
+build.usb_flags=-DUSB_VID={build.vid} -DUSB_PID={build.pid} '-DUSB_MANUFACTURER={build.usb_manufacturer}' '-DUSB_PRODUCT={build.usb_product}'