Zombie & Zombie Villager Self-Preservation

Currently, Zombie Villagers that naturally spawn in Zombie Villages will wander out during the day and burn to death. This happens even if the player is In Spectator or Creative mode. This results in Zombie Villagers found naturally to almost always die.

The behaviour of Zombie Villagers (and perhaps that of other sun-sensitive mobs) should be changed in a way that prevents them from attacking players during the day, when the player is not in shade or water and thus making those villages have more of a point, as well as making daytime mobs more of a challenge (if behaviour for all undead is modified).

TL,DR: Change sun-sensitive mob behaviour so that they will not give chase when they can die from sunlight.