[Adoption] Default physics variables

[Emojigit]

This PR is an adoption of #14767. This PR adds a minetest.DEFAULT_PHYSICS table so mods know the default values. The table is compatible with set_physics_override().

Closes #14764

To do

This PR is Ready for Review.

• minetest.DEFAULT_PHYSICS in Lua API
• Allow modifying the values

How to test

Run the unit test test_player_default_physics in devtest.

[Zughy]

My whole point is to allow mods to modify the value. Without, it's pretty useless for me

[Emojigit]

My whole point is to allow mods to modify the value. Without, it's pretty useless for me

Done in 917345d. But I wonder if the following code is guaranteed to run before any mods:

https://github.com/minetest/minetest/blob/917345d7e4e6634426a661ac7a4844768dc50fd3/builtin/game/default_physics.lua#L27-L29

[Zughy]

Wait, the change was already possibile without these commits. What I needed was simply a way to do minetest.DEFAULT_PHYSICS.foo = bar

[Emojigit]

Wait, the change was already possibile without these commits

Yeah, only the last commit is meaningful. I kept the previous commits only because I am too lazy to delete them.

[Zughy]

@Emojigit rebase needed

[Emojigit]

I have no idea how to fix whitespaces....