link between BR and PIO
new management of global ip storage for 6LoWPAN-ND

Optimization for Contiki of global ip in 6LoWPAN-ND.
Use routing table instead of neighbor cache.
Add micro table on 6LR to store global ip for duplication address request (retransmission).
shell
lifetime
some bug fixed
git ignore add .o
NC improvement
Add route in shell
Improve RT