boards: cleaned up LED handling for NRF5x based boards

netdev2: provide capability to pass up packet status information

doc: move details section to the top

boards/nrf51dongle: add xtimer configuration

stm32f3: periph: uart: add misssing uart overrun handling

drivers/kw2xrf: use NETOPT_STATE_RX for rcv

drivers: net: fix isr_arg for encx24j600 and ethos

color: add hex2color, color2hex, rgb2str, str2rgb

On overrung the ORE bit in the ORECF register is set.
An overrun error occurs when a character is received when RXNE has not been reset. Data
can not be transferred from the shift register to the RDR register until the RXNE bit is
cleared. The ORE bit is reset by setting the ORECF bit in the ICR register.

In case the ORE bit isn't cleared, the isr_handler() routine is called
continuously. Which prevents the system from normal scheduling.

boards/samr21-xpro: added third channel for PWM1

Details follow the brief section immediately now.

Add a layout file for Doxygen which has the details section at the
beginning of a page as opposed to the default where the details are
somewhere in the middle.

The initial XML file was generated as specified in the Doxygen
documentation:
```
doxygen -l
```

STM32 GPIO: Fix exti_isr handling to only call callbacks of lines with there IRQ enabled

netdev2_tap: fix strange event_callback argument

pba-d-01-kw2x: use GPIO_PIN for LED_*_GPIO

drivers/bh1750fvi: fix ingroup definition

drivers: make default radio channel configurable at compile time

gnrc_icmpv6: fix debug outputs

ndp: fix NCE creation on RA reception

drivers/gpio: changed default type to unsigned

RFC4861 says: "If a Neighbor Cache entry is created for the router
[while processing route advertisements], its reachability state MUST be
set to STALE as specified in Section 7.3.3."

drivers/mma8652: enhancements