ringbuffer: versatility and optimizations

There is no need for an explicit pointer to the end of the buffer.

It is a bad idea to use signed types for lengths.
Mark pointers a `restrict`, since the ringbuffer is not thread safe
anyway.

This patch add `peek` functionality, and empty and full helpers.

drivers: some improvements to the ADC driver interface

board - arduino-due: some cleanup

- removed unused defines

- added parenthesis for LED macros
- changed mapping for LED_* to LED_RED_*
- removed some old values from periph_conf.h

- removed UNDEFINED value from device enum
- added pre-defined precision values
- added power[on|off] functions
- some minor doxygen fixes

Reset ARM Cortex-M3 MCUs before flashing

drivers: added servo motor driver

sys/transcevier: fix more loop integers

native: uart reconnect buffer replay (+a little cleanup)

fix style
fix some syscall declarations
reorder syscall declarations
init syscalls in dedicated function
substitute 1 with EXIT_FAILURE

When using socket stdio, add option to replay what has been written to
stdout while not connected (`-r`).

The implementation is to simply use the existing log file (which is
implicitly created when the option is used), and read from it until
EOF upon reconnect.

closes #476

Fix a few cppcheck findings

native: clean up and clarify help

- reorder option details to mirror the order given in usage
- list option arguments in option details
- clarify option arguments

doc: mainpage.txt fixed minor mistake

examples: changed stacksize to the recommended value

ccnl: refactor ccn lite stack

ccnl: change timeouts to useful values

vtimer: fix crash on spurious hwtimer callback

Make filenames in periph documentation unique