FIB MPLS extension II

IP-MPLS interaction
    1) MPLS paths are stored in extended pathlists
    2) A seprate extended pathlist is allocated per IP prefix
    3) Extended pathlists contain minimum MPLS info and reply on IP pathlist for the rest info
    4) Extended Pathlists and MPLS LDI are shared

IGP LDI is not shared, BGP LDI is shared (memory usage .vs. Convergence)