Rename write_tag_value to write_tag_buf

We have not released this yet, let's align these names before it is too
late. The decoder adopted the `_buf` suffix and I find it more
convincing than the more generic `_value` (that also confusingly shares
it with `TiffValue`).

src/encoder/mod.rs

@@ -291,21 +291,6 @@ impl<'a, W: 'a + Write + Seek, K: TiffKind> DirectoryEncoder<'a, W, K> {
         })
     }
 
-    /// Write a tag-value pair with prepared byte data.
-    ///
-    /// Note that the library will _not_ attempt to verify that the data type or the count of the
-    /// buffered value is permissible for the given tag. The data will be associated with the tag
-    /// exactly as-is.
-    ///
-    /// An error is returned if the byte order of the presented value does not match the byte order
-    /// of the underlying file (i.e. the [native byte order](`crate::tags::ByteOrder::native`)).
-    pub fn write_tag_value(&mut self, tag: Tag, value: &ValueBuffer) -> TiffResult<()> {
-        let entry = self.write_entry_buf(value)?;
-        self.directory.extend([(tag, entry)]);
-
-        Ok(())
-    }
-
     /// Write a single ifd tag.
     pub fn write_tag<T: TiffValue>(&mut self, tag: Tag, value: T) -> TiffResult<()> {
         // Encodes the value if necessary. In the current bytes all integers are taken as native
@@ -330,6 +315,21 @@ impl<'a, W: 'a + Write + Seek, K: TiffKind> DirectoryEncoder<'a, W, K> {
         Ok(())
     }
 
+    /// Write a tag-value pair with prepared byte data.
+    ///
+    /// Note that the library will _not_ attempt to verify that the data type or the count of the
+    /// buffered value is permissible for the given tag. The data will be associated with the tag
+    /// exactly as-is.
+    ///
+    /// An error is returned if the byte order of the presented value does not match the byte order
+    /// of the underlying file (i.e. the [native byte order](`crate::tags::ByteOrder::native`)).
+    pub fn write_tag_buf(&mut self, tag: Tag, value: &ValueBuffer) -> TiffResult<()> {
+        let entry = self.write_entry_buf(value)?;
+        self.directory.extend([(tag, entry)]);
+
+        Ok(())
+    }
+
     /// Write some data to the tiff file, the offset of the data is returned.
     ///
     /// This could be used to write tiff strips. All of the data will be written into the file as a