Add domain entity editing functionality.

[ctrlaltdavid]

EntityServer API additions:

• [x] canRez, canRezTemp, and canGetAndSetPrivateUserData domain permissions properties.
• [x] canRezChanged, canRezTempChanged, and canGetAndSetPrivateUserDataChanged signals.
• [ ] addEntity() method.
  • [ ] Single packet. In progress.
  • [ ] Multiple packets.
• [ ] cloneEntity() method.
• [ ] editEntity() method.
  • [x] Single packet.
  • [ ] Multiple packets.
• [ ] deleteEntity() method.
• [ ] getEntityType() method.
• [ ] entityExists() method.
• [ ] EntityErase packet handling.

Entity property changes:

• [x] Add missing entity property, entityHostType.
• [x] Fix entity property name angularDampling -> angularDamping.
• [x] Fix entity property name cloneAvatarIdentity -> cloneAvatarEntity.
• [x] Rename Model entity's animation properties: animation.animationURL -> animation.url, etc.
• [x] Fix grab-related properties (grabbable, grabKinematic, ...) so that they are in a grab property group (same as native scripting API) rather than at root level and fixed up names.

Example app:

• [x] Report domain permissions properties.
• [ ] Add, clone, edit, and delete example entity actions. In progress.