Disable system stepping feature by default

[alice-i-cecile]

What problem does this solve or what need does it fill?

This feature should not be included in shipped games, and adds small but measurable performance overhead to running schedules.

What solution would you like?

Disable the feature by default, and document that you need to enable it in the example.

What alternative(s) have you considered?

Add this to your Cargo.toml, and update it every release:

default-features = false
features = [
  "animation",
  "bevy_asset",
  "bevy_audio",
  "bevy_gilrs",
  "bevy_scene",
  "bevy_winit",
  "bevy_core_pipeline",
  "bevy_pbr",
  "bevy_gltf",
  "bevy_render",
  "bevy_sprite",
  "bevy_text",
  "bevy_ui",
  "multi-threaded",
  "png",
  "hdr",
  "vorbis",
  "x11",
  "bevy_gizmos",
  "android_shared_stdcxx",
  "tonemapping_luts",
  "default_font",
  "webgl2",
]

Additional context

Any other information you would like to add such as related previous work,
screenshots, benchmarks, etc.

[iiYese]

Is disabled really the better default tho? Release builds are the exception not debug builds.

[alice-i-cecile]

Disabling features of your dependencies in Rust is particularly painful: if it's not on the core path I'd prefer to keep it out.

In particular, when building my games I like to have a dev-mode feature in my own crate. In order for that to work correctly, I now need to disable all default features, and carefully select my options.