This is an effort to automate UART testing using the same framework as
was already introduced for i2c. The framework relies on shell commands
to return invocation status and data in a special way:
1. Invocation status: Success or Error
2. Data inside the []
Hence this patch adds invocation status to the UART init command and
invocation status and data to the printer.
Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
uart0 functionality is removed by #3164. This patch implements periph/uart,
rather than deprecated uart0, using /dev/tty.
To use with netdev2_tap simultaneously, this patch adds asynchronus read system
and modifies netdev2_tap to use it.
A TTY device is specified on command line with -c (COM) option, since -t was
used by the old implementation.
This patch also implements empty GPIO driver needed by the xbee driver.
