Multiverse compatibility

* bumped version to 3.9.2
* Internal rework: the whole Lanes engine now works "per universe" to
allow concurrent Lanes execution in more than one embedded master state
* this universe is a full userdata created in the master state,
selfdestruct_gc is the __gc for this userdata
* most of what was initialized only once is now per-universe
* Fixed potential crashes at desinit if problems occur during keeper
states initialisation
* Fixed require() not always serialized properly
* Raise an error instead of crashing on deep userdata prelude memory
allocation failure
* Added forgotten mutex desinitialisation at universe shutdown