Added an API for getting a callback when a ping reply is received.
Stopped to load plugins depending on simulations if there is no simulation
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.
collect: making some protocol parameters configurable by COLLECT_CONF_ style defines

TTL (which has a rather low default of 15), MAC level retransmissions,
overall number of retransmissions, and the header bits dedicated to these
were all fixed in the collect.h and collect.c, without a simple way to
override them.
Extracted these as COLLECT_CONF_ parameters, keeping defaults as they were
before.

Signed-off-by: Csaba Kiraly <kiraly@disi.unitn.it>
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.
rl78: Rename CORE to RL78_CORE to avoid a conflict with Contiki's CORE variable.
eval-adf7xxxmb4z: Corrections to the platform README, update URLs to point to the mainline Contiki.
rl78: Attempt to locate the IAR installation automatically and instruct the user how to specify IAR_PATH if it cannot be found.
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
Merge pull request #538 from cskiraly/collect-fixes

collect: making some protocol parameters configurable by COLLECT_CONF_
eval-adf7xxxmb4z: Use the nullrdc driver instead of sicslowmac.
Adds  encoding attribute utf-8 arg to cooja compile command
Merge pull request #544 from drakkar-lig/cooja-compile-error

Cooja compile error
Merge pull request #532 from darki2002/Plugin_sim

Stopped to load plugins depending on simulations if there is no simulation