WIP: Upgrade to bevy 0.13

[nerdachse]

Hello!

Sadly this isn't merge-able as is, due to the fact that it crashes:

called `Option::unwrap()` on a `None` value
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Encountered a panic in system `vx_bevy::voxel::world::meshing::process_mesh_tasks`!
Encountered a panic in system `bevy_app::main_schedule::Main::run_main`!
[Finished running. Exit status: 101]

But it's a start at least :)

[Game4all]

Changes look good to me so far. Could you please look at fixing the clippy warnings ? Thanks!

[nerdachse]

@Game4all I would but as said, even though it compiles, it crashes with an unwrap on none.

Haven't had time to look into it yet

[Game4all]

no worries :)