Replace 'clone_from_slice' with 'copy_from_slice'
Currently, 'shared_memory::safe_copy' uses 'clone_from_slice' to
perform memory copy. 'clone_from_slice' iterates over each element of
slice to invoke 'clone_from'. According to docs of 'clone_from_slice', it can be
more performant to use 'copy_from_slice' instead when target slice
implements 'Copy'(https://doc.rust-lang.org/std/primitive.slice.html#method.clone_from_slice).
Since '&[u8]' implements 'Copy', I thought replacing 'clone_from_slice'
with 'copy_from_slice' would be a helpful change regarding
performance.

Thank you for reviewing this PR :)
diff --git a/core/src/shared_memory.rs b/core/src/shared_memory.rs
index 76e710e..cac849d 100644
--- a/core/src/shared_memory.rs
+++ b/core/src/shared_memory.rs
@@ -42,5 +42,5 @@
     let amount = origin.len().min(destination.len());
     let origin = &origin[0..amount];
     let destination = &mut destination[0..amount];
-    destination.clone_from_slice(origin);
+    destination.copy_from_slice(origin);
 }