Merge branch 'PrepareForIDE1.6' (PR#2306)

.travis.yml

ArduinoAddons/Arduino_1.6.x/hardware/marlin/avr/boards.txt

.../hardware/marlin/avr/bootloaders/SAVMkI/BootloaderHID.hex

...rdware/marlin/avr/bootloaders/SAVMkI/SAVMkI-1286-LUFA.hex

...6.x/hardware/marlin/avr/bootloaders/SAVMkI/SAVMkI-CDC.hex

...hardware/marlin/avr/bootloaders/at90usb/BootloaderHID.hex

...are/marlin/avr/bootloaders/at90usb/Brainwave-646-LUFA.hex

...marlin/avr/bootloaders/at90usb/BrainwavePro-1286-LUFA.hex

...x/hardware/marlin/avr/bootloaders/atmega/ATmegaBOOT_168.c

...lin/avr/bootloaders/atmega/ATmegaBOOT_168_atmega1284p.hex

.../avr/bootloaders/atmega/ATmegaBOOT_168_atmega1284p_8m.hex

...rlin/avr/bootloaders/atmega/ATmegaBOOT_168_atmega644p.hex

...ino_1.6.x/hardware/marlin/avr/bootloaders/atmega/Makefile

...Arduino_1.6.x/hardware/marlin/avr/cores/arduino/Arduino.h

...s/Arduino_1.6.x/hardware/marlin/avr/cores/arduino/CDC.cpp

.../Arduino_1.6.x/hardware/marlin/avr/cores/arduino/Client.h

...s/Arduino_1.6.x/hardware/marlin/avr/cores/arduino/HID.cpp

....6.x/hardware/marlin/avr/cores/arduino/HardwareSerial.cpp

..._1.6.x/hardware/marlin/avr/cores/arduino/HardwareSerial.h

...6.x/hardware/marlin/avr/cores/arduino/HardwareSerial0.cpp