Async Data Read for Parallel World Ticking

[Taiyou06]

This PR should improve the compatibility of the plugins that just READ THE DATA of world and not write.

It adds an option called async-unsafe-read-handling default value is STRICT and to use the new buffer handling switch it to BUFFERED.

Please report any compatibility issues when it's set to BUFFERED and PWT is off (just to be sure that we don't change any behaviours when it's off)