FOSS gamedev and creative worlds

See https://forum.minetest.net/viewtopic.php?f=18&t=16595 for more details.
This PR is now being merged.

"To introduce the new flags I had to increase the map block serialization version, this is why you can not play on your maps on other versions of Minetest after you opened them in this version.
Of course old clients still can play, just the server has to be new to be able to read the map."

This includes singleplayer.

In simple words, if you open your world with today's dev build (as of f17c9c4), there's no easy way back to older minetest version. If you want to be safe - make a backup of your world.

Why devs decided this? Those changes are needed to fix long standing annoying lighting/shadows bugs that plagued minetest for years, they will fix:
+ ghost light after lava casts (with this PR)
soon:
+ L-system trees incorrect shadows, moretrees will work out of the box
+ incorrect light after tnt in water explosion
+ squarish shadows induced by tnt blown over to far horizon
+ ghost light after sofar's lightning mod strike
+ lighting bugs in other scenarios

Good to know you are going actively killing all those light bugs. :-)
It is totally worth it to introduce the incompability IMO, because those light bugs are, as you put it nicely, quite a plague.


By the way: So once I go to the dev version, there's no way back, but what about the other way around?
What happens if I use a 0.4.15 world with the development version? Could there be possible problems?

The L-system tree bug is fixed? YEAH

What happens if I use a 0.4.15 world with the development version? Could there be possible problems?

Should be no problems, it just works...

Correct, no problems with that.