Fix coding conventions in sys/transceiver/transceiver.c
Allow IEEE 802.15.4 addressing types for transceiver

IEEE 802.15.4 has two addressing modes: 16-bit short and the device's
EUI-64. Currently RIOT supports only sending of packets with 16-bit
short addresses via the transceiver interface. This patch allows at
least for the radio chips that support IEEE 802.15.4 to let the
application/upper layer decide which addressing mode to use.

Upper layer implementation will be implemented in follow-up PR to #460
Add getter and setter of long addresses to transceiver
Implement net_if module
Add shell commands for interface configuration
Add test cases for net_if module
Fix coding conventions for sixlowpan and rpl module
Fix ieee802154_frame module
Put 6LoWPAN border router in its own module
Decouple ICMPv6 from 6LoWPAN
Add capability to set and get variable default hop limit
Use net_if in 6LoWPAN MAC layer
Use net_if in 6LoWPAN layer
Byte order and rpl problems
Let IPv6 and ICMP use new 6LoWPAN layer (+fixes)
Add sixlowpan to auto_init
Fix apps for previous changes
nbr_cache_auto_rem does not need an extra thread
Eliminate side effects in icmpv6_csum and make it public
Merge pull request #460 from authmillenon/define_ll_ifs

Link layer interfaces