mrouted v4.5

Fixes

• Ignore IGMP proxy querys (src ip: 0.0.0.0), they must never win a
  querier election.
• Fix compat read location and new location for mrouted.genid
• Fix "non-decreasing" generation id, must increment on each restart

Changes

• Add support for configurable IGMP query response interval
• Add support for configurable IGMP querier timeout
• New join-group <group> phyint option for cases where an IGMP
  snooping switch blocks flooding of multicast to the port where
  mrouted is connected
• On startup and reconf, log why we skip disabled interfaces
• Change to always log when assuming the IGMP querier role