rewrite bed compat code

[BuckarooBanzay]

This PR rewrites the beds compatiibilty code to the new movenode-definition and callback system (see here: https://github.com/mt-mods/jumpdrive#movenode-compatibility and here: https://github.com/mt-mods/jumpdrive#hooks)
The new API removes lots of duplicate and expensive calls to minetest.find_nodes_in_area and should make jumping faster in general while also providing a generic way to listen to movement events.

I ended up rewriting larger portions of the code you made @tuedel (sorry 😋)
Let me know if you have issues/suggestions with the way it is now

The new file is best viewed standalone and not as diff:
https://github.com/mt-mods/jumpdrive/blob/bed-compat-ng/compat/beds.lua

NOTE: this isn't tested yet, only a first draft

[tuedel]

Sure, go ahead 😉 My code was just quickly hacked together, I was planning on rewriting/simplifying it anyway.

[tuedel]

The sleeping position has changed in minetest/minetest_game@9bf64b6, but just setting y = y + 0.07 and using vector.equals() to check didn't work for me because of floating point (im)precision.

I solved this on my server by just rounding down y for the check:

if sleep_pos.x == player_pos.x and
    math.floor(sleep_pos.y) == math.floor(player_pos.y) and
    sleep_pos.z == player_pos.z then

[...]

This conveniently also keeps backwards compatibility with the old sleeping positions.

[SwissalpS]

At this sate it seems to work.
What I was not able to test, is how players, currently in bed(s), are treated during a jump.
(Yes multiple players can be in multiple or the same one at the same time)