Removed all `#![feature]` flags, except for `#![feature(test)]`. Once parser benchmarks are ported to something that is compatible with stable rust, we will be able to switch to it.
This PR updates the Rust toolchain to recent nightly.
Most of the changes are related to fixing newly added warnings and adjusting the feature flags. Also the formatter changed its behavior slightly, causing some whitespace changes.
Other points:
* Changed debug level of the `buildscript` profile to `lint-tables-only` — this should improve the build times and space usage somewhat.
* Moved lint configuration to the worksppace `Cargo.toml` definition. Adjusted the formatter appropriately.
* Removed auto-generated IntelliJ run configurations, as they are not useful anymore.
* Added a few trivial stdlib nightly functions that were removed to our codebase.
* Bumped many dependencies but still not all:
* `clap` bump encountered https://github.com/clap-rs/clap/issues/5407 — for now the warnings were silenced by the lint config.
* `octocrab` — our forked diverged to far with the original, needs more refactoring.
* `derivative` — is unmaintained and has no updated version, despite introducing warnings in the generated code. There is no direct replacement.
Use the new Enso Font; also change the anti-aliasing logic to be based on device pixel ratio, rather than platform. This will improve the clarity of font rendering on Windows/Linux machines with high pixel densities.
Design reference:
Tested on various combinations of DPR/platform:
OS X, `devicePixelRatio` = 2 (should look similar to how we were already rendering *mplus1* on OS X):
<img width="1440" alt="Screenshot 2023-08-07 at 5 46 11 PM" src="https://github.com/enso-org/enso/assets/1047859/2fdf251a-ba5e-426f-b6c4-194347a9cee4">
Windows, `devicePixelRatio` = 1.25 (should look similar to how we were already rendering *mplus1* on this platform/DPR):
Linux, `devicePixelRatio` = 1 (should look similar to how we were already rendering *mplus1* on this platform/DPR):
# Important Notes
Style changes:
- Use the Enso Font for code in Rust, replacing the DejaVu fonts.
- Use the Enso Font in HTML: code in documentation, and error visualizations.
- Change SpanWidgets from Bold to Extra Bold, to match the design.
Implementation improvements:
- The new font download is cached (and Github-authenticated); this should eliminate a "rate limit" build failure I've
encountered in the past.
- Clean up DocSection HTML rendering a bit.
- Remove a CSS file that seems to have been superseded.
