introduced EntityViewStruct
cut a lot of code not needed anymore
breaking change engines add and remove callback now accept only ref params
breaking change QueryEntityViewsAsArray renamed in to QueryEntityViewsCacheFriendly

- introduced the concept of global ID, as a combination of groupID and entityID
- only 256 groups and 2^24 entities can be created
- all the entities are now built always in group, when the group is not specified, the "standard" groups is used
- the groupID can be retrieved from the EGID
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