fixed sixlowpan address initialization

 * prevent that IPv6 address gets overwritten when configuring as adhoc router
 * additional debug information about assigned IPv6 addresses
Merge pull request #263 from OlegHahm/sixlowpan_fixes

sixlowpan address initialization
very dirty hack to use ZEP header
fixed byte order for ieee802.15.4 frame
correct byte order for IPv6 length field
Refactor destiny/in.h
Refactor destiny/socket.h
Order includes in destiny
added some debug output for the network stack
added missing ZEP header file
adapted include pathes
correct byte order for UDP length field

Conflicts:
	sys/net/destiny/socket.c
sixlowpan address initialization and NHC

 * prevent that IPv6 address gets overwritten when configuring as adhoc router
 * introduce NHC field
fixing include pathes for destiny
correct byte order for UDP header and prefer higher ports
prepared UDP NHC (not finished)