arduino/Arduino — pull request #2511 by collin80 (2014-12-24 15:40:13+00:00)
Title: Transmit interrupt for UART and USART. Merge UART/USART

Increased ringbuffer size to 128 for the Due.

Merged UARTClass and USARTClass as much as possible to keep duplicate code to a minimum.

Implemented interrupt driven transmission over all hardware serial ports.