Jeryn Aldaron Lau

https://docs.rs/twang/latest/twang/struct.Synth.html

This should at least be possible with the current fon API, but maybe not optimal.

And figure out a way to not run futures in `Drop`.

~https://github.com/rust-lang/rust/issues/93178 (remove pin-utils dependency when **`no-std`** is enabled)~ - [ ] https://github.com/rust-lang/rust/issues/86918 (remove `Unpin` requirement for `Notifier` impl on `Pin`)

Supports compiling pasts to no-std on stable with a feature flag to pull in faux_alloc. This removes the need for all the nightly boilerplate. Closes https://github.com/ardaku/pasts/issues/18

When creating the `Executor`, it should be possible to set a limit on the number of spawned tasks to avoid allocation. Setting the limit to zero should fallback to using...

Because we have [`Arc::from`](https://doc.rust-lang.org/std/sync/struct.Arc.html#impl-From%3CT%3E), [Executor::new()](https://docs.rs/pasts/0.11.0/pasts/struct.Executor.html#method.new) can take `Into Arc`, and pass an `Arc` created outside the global allocator in the no-std example.