Implementation of the Trickle multicast engine
Implement multicast engine hooks in the uIPv6 core

  - init()
  - process incoming multicast datagram
  - Pass ICMPv6 trickle messages to the engine
Multicast README
IPv6 Multicast Example
Multicast compile regression tests
Minor code style fixes
Simple regression test for the IPv6 multicast code with 12 nodes (11 hops) in a line configuration
Simple regression test for the IPv6 multicast code with 32 nodes (31 hops) in a line configuration
Don't wait for a specific packet (which may not arrive) - instead, wait for any packet to arrive.
Point to the correct trickle param
Improve sliding window inclusion in ICMPv6 messages

Don't include a sliding window in the ICMPv6 datagram
unless the window has at least one active datagram
associated with it
Don't advertise datagrams older than Tactive
Check Tactive irrespective of suppression
Update regression sims to org.contikios
Factor out multicast stats