MobsToEggs 1.6.6_2 - PATCH fixed egg data and custom eggs not working correctly.
UPDATED:
Fixed the issue with spawn egg data not applying to mobs when spawned.
Fixed custom spawn eggs not spawning mobs.
Spawner changing has subsequently broken and will be fixed later.
Opening container blocks while holding a MobsToEggs spawn egg will once again spawn the mob instead of opening the container. This will also be fixed later.