Worlds: controlling update sequence.

[Yanrishatum]

I'm lack of controlling update sequence in Worlds, and added some functions to control it. In perfect way - there must be something like layers for update sequences, but it's to complicated.
I'm made next functions:

• Bring entity to be updated first.
• Send entity to be updated last.
• Bring entity forward one step (updated earlier).
• Send entity backward one step (updated later).
• Bring entity to be updated before second entity.
• Send entity to be updated after second entity.
• Swap two entities in update sequence.

Source: http://pastebin.com/02LePwHE
I apologise for external site URL. I didn't want to make a fork or post all code, because it takes too many space.

[citiral]

I agree, these functions can really come in handy for some entities that need to get update priority. I'd say make a branch and pull request right away