[no_alloc]: Extend support for embedded systems by removing the need for alloc

[dbongartz]

TL;DR: An option to compile without feature = "alloc" would be great :)

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There is a feature flag for alloc already but it's not completely implemented.

A modified basic example (using a *mut self reference) compiles if I #[cfg(feature = "alloc")] out the use core::alloc::{...} and impl for Box, Rc, ... in mod.rs. But there are other parts which might need to be adjusted.

Reduced feature set would be fine IMO as the most basic is already nice enough to just wrap self-referencing types from C FFI on the stack.

I'm not well versed all these macro-magic though :)

[silvanshade]

There is a fork at https://github.com/silvanshade/moveref that has #[no_std] support.