Scan new "entities" folders (>=1.17), fix scan of "poi" folders

[ghost]

Hello ! ^^
This PR is the following of #166 (Even if it works without) and ends issue #165 (Please read it first).
It also fixes the scan of the poi folder for dimension.

Main changes :

• poi isn't considered as a dimension anymore. I created a new system (Like dimensions) called "region files type", with currently 3 types : Regions (Level), POIs and Entities. Each dimension (Including the overworld) can have those 3 types or MCA files (Respectively stored in region, poi and entities).
• This types system contains entities files, which is new.
• RegionSet objects are differentiated by dimension AND type. This is especially used for wrong located or corrupted chunks replacement from a backup.
• scan_chunk() can now recognize and analyze MCA files from entities. The differentiating factor is the presence of the Entities tag at the root of the chunk. For a region/level file, it is in the Level tag.
• get_number_regions() now differentiate regions by type. It now returns a dictionary.
• delete_entities() can be also used for entities MCA files.

I didn't test, but this commit should also fix issue #162.

Really important note, as last time : I am still not familiar with the Region-Fixer code and architecture, so this commit can possibly lead to problems and bugs. Thanks @Fenixin to be careful before merging this PR. ^^

Have a nice day ! ^^

[Fenixin]

Hey! Thanks a lot for your contribution!

I'll test and check both pull requests in the next few days and merge if nothing explodes.

Thanks again!

[ghost]

You're welcome. ^^
I tested it, but I don't think it's enough.
I think you should also read my code carefully, because you're the original developer, so you know better than me how everything works. So take your time ! :D
You can tell me if there are things I can improve, or if you wish, you can directly push on my repo to make some edits. ;)
Have a nice day !

[Fenixin]

The changes seem to work perfectly well, there is only a small problem in summary() while generating the log for the overworld, I'll push a fix just now.

Thanks a lot for the changes! Nicely done and works like a charm!

Edit: not in summary, but in RegionSet.get_name()

[ghost]

It's great, thank you very much ! :D