Pull copyout out of IFNET_LOCK and replace IFNET_LOCK with IFNET_RENTER
Replace IFNET_LOCK with IFNET_RENTER by using refcount
Describe ifnet locking rules and ifget/ifput/ifhold
Add comment to m_reclaim
Fix sysctl_dumpentry of rt
Introduce ifget_byindex
Tweak sysctl_dumpentry
Replace if_attach of if_tap with if_initialize and if_register