Fix dead ongen saplings due to biome_lib secession

[debagos]

I recently updated moretrees and noticed that the ongen_saplings that were already present prior to the update never grow anymore.

This is a big thing for me because over months I slowly let the whole map surface generate, without activating the newly generated areas. So there are dead ongen saplings everywhere on the map...

The dimension of this problem is very unique to my server because of the pre-generated map, but I expect dead saplings on other publicly hosted servers as well, due to how biome_lib works (see: biome_lib_queue_ratio). There are more reasons to why an ongen saplings hasn't grown yet than a pre-generated map (eg. NodeTimer not run yet due to high lag or a server shutdown/crash).

My solution to this issue is adding a unique group to those ongen saplings and let a LBM kick them active. Furthermore I added a setting to enable the mentioned LBM. The LBM isn't enabled per default, to not create unnecessary overhead for simple and small scale users of this mod, while providing a simple fix for people like me.

[BuckarooBanzay]

A few line-too-long errors here: https://github.com/mt-mods/moretrees/actions/runs/7485615804/job/20379754526?pr=35 not sure if they should be fixed or just the min-length increased, i'm fine with both :)

How rare is that use-case? Could it be something that could be done in a standalone mod perhaps (not suggesting this, just figuring out who else would have that problem too)

[debagos]

A few line-too-long errors

Oops, that's fixed now.

How rare is that use-case?

I think it's a pretty rare use case, but like I said I expect to see dead saplings not just on my own server. Let me give you an explaination on what can cause dead saplings:

• All saplings spawned between https://github.com/mt-mods/moretrees/commit/e476b81cf5270adf34b3a19573abf52fbfdfee9d and https://github.com/mt-mods/moretrees/commit/d43b79f4d2c4eb214f63c465e73c494a6d00ece1 are non-functional if ethereal, nether or any other mod was installed that incautiously uses/used minetest.clear_registered_decorations()
• Saplings spawned with moretrees prior to https://github.com/mt-mods/moretrees/commit/e476b81cf5270adf34b3a19573abf52fbfdfee9d who have not had their node timers ran until the mod got updated.

To elaborate a little bit further, here are two reasons why a saplings node timer may never have ran:

• Area got generated but server hard-crashed (SIGKILL, OOM, LuaJIT anyone?) and the area never getting activated again until the mod got updated (reasons could be: player never rejoined or pre-crash saved player position is outside the range of the sapling).
• biome_lib itself. Sometimes when a player explores and the lag is high an area gets deactivated before biome_lib is done. The reasons is how biome_lib tries to keep the lag low and delays stuff. If you want to get into how that works, have a look at biome_lib_queue_ratio. I have seen that a lot on my server, because I am using a rather strict biome_lib_queue_ratio.

  Could it be something that could be done in a standalone mod perhaps

That would work, yes. I personally prefer the in-mod fix, but I wouldn't mind rejecting this PR completely and rely on the admins themselves to notice and fix the issue. But that would leave people who aren't able to come up with a simple mod who fixes those broken saplings pretty much on their own.

Oh and I would like to mention that @Niklp09 gave me the idea of the LBM after he learned about me having this issue.