automatically inherit VRF from pool in nipapd
automatically inherit VRF from pool in nipapd

When allocating from a pool, nipapd now looks at the implied VRF of a
pool and sets the same VRF to the new prefix being allocated. It doesn't
work for from-prefix operations as the input argument to from-prefix is
a list of prefixes and not a list of IDs of prefixes, so they can only
be uniquely identified by being specified in combination with a VRF.

Part of #286

bbaja42/NIPAP,ettrig/NIPAP,ettrig/NIPAP,SpriteLink/NIPAP,bbaja42/NIPAP,SpriteLink/NIPAP,garberg/NIPAP,ettrig/NIPAP,garberg/NIPAP,SoundGoof/NIPAP,fredsod/NIPAP,SoundGoof/NIPAP,ettrig/NIPAP,fredsod/NIPAP,plajjan/NIPAP,fredsod/NIPAP,ettrig/NIPAP,plajjan/NIPAP,SoundGoof/NIPAP,SoundGoof/NIPAP,garberg/NIPAP,plajjan/NIPAP,garberg/NIPAP,SoundGoof/NIPAP,bbaja42/NIPAP,garberg/NIPAP,SoundGoof/NIPAP,bbaja42/NIPAP,ettrig/NIPAP,plajjan/NIPAP,fredsod/NIPAP,fredsod/NIPAP,SpriteLink/NIPAP,bbaja42/NIPAP,plajjan/NIPAP,garberg/NIPAP,fredsod/NIPAP,bbaja42/NIPAP,SpriteLink/NIPAP,SpriteLink/NIPAP,SpriteLink/NIPAP,plajjan/NIPAP