Style fixes
contikimac: Removed redundant memb_free
llsec: Added a layer in between NETSTACK_MAC and NETSTACK_NETWORK for implementing link layer security
llsec: Configuration option for defining a constant LoWPAN-wide security level
llsec: Added encryption security levels
llsec: Hardware-independent interface to the symmetric-key
algorithms of 802.15.4
llsec: Reusable LLSEC_CCM.aes-based implementations of CCM*
llsec: Reusable functions for settings keys that are smaller
than 128 bits and for calling AES with plaintext blocks that are
smaller than 128 bits
sky-main: Calling NETSTACK_LLSEC.bootstrap from contiki-sky-main.c
sky-main: DEBUG on/off switch
packetbuf: Added security-related attributes
framer-802154: Defferring hdrreduce, so that an llsec_driver can access the entire frame
framer-802154: Support for creating and parsing frames with security
headers
framer-802154: Support for setting and accessing the frame type
attribute
framer-802154: Sequence number fixes
framer-802154: Renamed variable
framer-802154: Simplification of frame802154_create
framer-802154: Supporting key identifier mode 1
framer-802154: Calling NETSTACK_LLSEC.on_frame_created()
CC2420: Doing CRC in hardware all the time