On the lua side, notably minetest.env:<function>(<args>) should now
be replaced by minetest.<function>(<args>).
The old way is and will stay supported for a long time.

Also:
Update and clean up lua_api.txt (by celeron55)
Move EnvRef to lua and remove add_rat and add_firefly (by kahrl)
Add separate src/util/CMakeLists.txt, other minor fixes (by kahrl)

Add a Way of checking for specific Feature with Lua Adds minetest.get_feature() and minetest.has_feature()

When accidentally misspelling a name, privileges are sometimes granted to non-existent players, leaving them with the extra privileges, but without the default privileges, if they ever join the server. This corrects that by disallowing /grant from working with invalid players. For completeness, it does the same for /revoke.

When first entering an area, sometimes placing nodes replaces other nodes that are not buildable_to. This seems to be caused by the fact that nodes in unloaded map blocks are treated as ignore, a node that is buildable_to. This fixes that, by using get_node_or_nil() instead of the previously-used get_node(), then checking to see if the nodes were actually loaded before replacing.

Drop nodes as items when dugged and no room in inventory and dont remove dropped items when no room in inventory

Nodes in this group will be dropped as items if the node under them or the node in the wallmounted direction is not walkable.