Added an API for getting a callback when a ping reply is received.
Fix buggy UART baudrate calculation in the RL78 UART driver.
Increase the default baudrate to 38400 bps for RL78.
Add cpu/rl78/dev/uart1.h because some examples rely on it.
Merge pull request #534 from hexluthor/rl78-fixes

UART-related fixes for Renesas RL78
Copied 'contiki_arg[c|v]' from 'native' to the other desktop targets.

- On the retro targets support for 'contiki_arg[c|v]' is optional as accesing arg[c|v] is rather expensive.
Merge pull request #536 from oliverschmidt/master

Copied 'contiki_arg[c|v]' from 'native' to the other desktop targets.
Added cmdline args support to wget example.
Merge pull request #537 from oliverschmidt/master

Added cmdline args support to wget example.
Added more flexibility to webbrowser -> wget forwarding.

- Up to now the CTK program handler was necessary to start wget and forward the URL. Now alternatively the webbrowser uses the underlying OS to exec wget.

- Up to now windowed CTK was necessary to display the acknowledge dialog. Now alternatively the webbrowser displays the acknowledge text and buttons right in the webpage area.

- For now the targets 'win32' and 'c64' make use of the new capabilities.
Merge pull request #539 from oliverschmidt/master

Added more flexibility to webbrowser -> wget forwarding.
Fix compilation error when DEBUG enabled in core/net/mac/framer-nullmac.c
Merge pull request #541 from drakkar-lig/degug-compile-error

Fix compilation error when DEBUG enabled in core/net/mac/framer-nullmac....
Merge pull request #504 from adamdunkels/push/ping-reply-api

A ping reply API