make crate no_std supporting for nalgebra -> ndarray use case

Cargo.toml

@@ -7,7 +7,7 @@ description = "Conversion between n-dimensional types in different Rust crates"
 documentation = "https://docs.rs/nshare/"
 repository = "https://github.com/rust-cv/nshare"
 keywords = ["ndarray", "nalgebra", "image", "convert", "borrow"]
-categories = ["rust-patterns"]
+categories = ["rust-patterns", "no-std"]
 license = "MIT"
 readme = "README.md"
 

src/lib.rs

@@ -1,3 +1,5 @@
+#![no_std]
+
 #[cfg(feature = "nalgebra")]
 mod tonalgebra;
 #[cfg(feature = "nalgebra")]

src/tonalgebra/ndarray_impl.rs

@@ -2,8 +2,8 @@
 
 use super::*;
 
+use core::convert::TryFrom;
 use nalgebra::Dynamic as Dy;
-use std::convert::TryFrom;
 
 /// ```
 /// use nshare::ToNalgebra;

src/tondarray/image_impl.rs

@@ -1,9 +1,13 @@
 //! Implementations for conversions from image types to ndarray types.
 
 use super::*;
+use core::ops::{Deref, DerefMut};
 use image::{flat::SampleLayout, ImageBuffer, Luma, Pixel, Primitive};
 use ndarray::{Array2, Array3, ArrayView2, ArrayView3, ArrayViewMut2, ArrayViewMut3, ShapeBuilder};
-use std::ops::{Deref, DerefMut};
+
+extern crate alloc;
+
+use alloc::vec::Vec;
 
 /// ```
 /// use image::GrayImage;