feat/tensor: implement IntoTensorDesc for [usize; N], N=1...6

Currently dimensions of a tensor can be specified with usize, tuples, Vecs
and slices:
SharedTensor::new(backend, &10)
SharedTensor::new(backend, &(10, 2))
SharedTensor::new(backend, &vec![10, 2])

In cases like this, vec! causes an unneeded allocation and is a bit more
verbose than possible. Usize/tuple syntax looks somewhat irregular. It would
be nice to be able to express tensor creation like this:
SharedTensor::new(backend, &[10, 2])
But Rust doesn't autocoerce &[usize; _] into &[usize]. This patch adds explicit
implementations to make this use case work.

Package version is also bumped to make it possible to depend on this feature.

Author: alexandermorozov

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name          = "collenchyma"
 description   = "high-performance computation on any hardware"
-version       = "0.0.8"
+version       = "0.0.9"
 authors       = ["Michael Hirn <mj@autumnai.com>",
                  "Maximilian Goisser <max@autumnai.com>"]
 

src/tensor.rs

@@ -201,6 +201,20 @@ impl IntoTensorDesc for (usize, usize, usize, usize, usize, usize) {
     }
 }
 
+macro_rules! impl_array_into_tensor_desc {
+    ($($N:expr)+) => {
+        $(
+            impl IntoTensorDesc for [usize; $N] {
+                fn into(&self) -> TensorDesc {
+                    let slice: &[_] = self;
+                    From::from(slice)
+                }
+            }
+        )+
+    }
+}
+impl_array_into_tensor_desc!(1 2 3 4 5 6);
+
 impl ITensorDesc for TensorDesc {
     fn rank(&self) -> usize {
         self.len()