Renamed AMfreeResult() to AMresultFree().

Remove the `&AMchange` conversion for `AMbyteSpan`.
Add a `&automerge::ActorId` conversion to for `AMbyteSpan`.
Remove the `&Vec<u8>` conversion for `AMbyteSpan`.
Add a `&[u8]` conversion for `AMbyteSpan`.

automerge-c/src/byte_span.rs

@@ -1,16 +1,14 @@
 use automerge as am;
 
-use crate::AMchange;
-
 /// \struct AMbyteSpan
 /// \brief A contiguous sequence of bytes.
 ///
 #[repr(C)]
 pub struct AMbyteSpan {
     /// A pointer to an array of bytes.
-    /// \warning \p src is only valid until the `AMfreeResult()` function is called
-    ///          on the `AMresult` struct hosting the array of bytes to which
-    ///          it points.
+    /// \warning \p src is only valid until the `AMresultFree()` function is
+    ///          called on the `AMresult` struct hosting the array of bytes to
+    ///          which it points.
     src: *const u8,
     /// The number of bytes in the array.
     count: usize,
@@ -25,10 +23,13 @@ impl Default for AMbyteSpan {
     }
 }
 
-impl From<&AMchange> for AMbyteSpan {
-    fn from(change: &AMchange) -> Self {
-        let change_hash = &(change.as_ref()).hash;
-        change_hash.into()
+impl From<&am::ActorId> for AMbyteSpan {
+    fn from(actor: &am::ActorId) -> Self {
+        let slice = actor.to_bytes();
+        Self {
+            src: slice.as_ptr(),
+            count: slice.len(),
+        }
     }
 }
 
@@ -51,11 +52,11 @@ impl From<&am::ChangeHash> for AMbyteSpan {
     }
 }
 
-impl From<&Vec<u8>> for AMbyteSpan {
-    fn from(v: &Vec<u8>) -> Self {
+impl From<&[u8]> for AMbyteSpan {
+    fn from(slice: &[u8]) -> Self {
         Self {
-            src: (*v).as_ptr(),
-            count: (*v).len(),
+            src: slice.as_ptr(),
+            count: slice.len(),
         }
     }
 }