Qualify OwnedCharsExt::into_chars calls

Shuts up some warnings.

Author: smheidrich

src/suitable_seekable_buffered_text_stream.rs

@@ -41,7 +41,7 @@ impl Utf8CharSource for SuitableSeekableBufferedTextStream {
             // becomes 0? => no seek), but probably not relevant
             self.buf_start_seek_pos = Some(self.inner.seek(OpaqueSeekFrom::Current)?);
             let buf = self.inner.read_string(self.buffer_size)?;
-            self.chars_iter = buf.into_chars();
+            self.chars_iter = OwnedCharsExt::into_chars(buf);
             self.chars_read_from_buf = 0;
             let oc = self.chars_iter.next();
             if oc.is_some() {

src/suitable_unseekable_buffered_text_stream.rs

@@ -35,7 +35,7 @@ impl Utf8CharSource for SuitableUnseekableBufferedTextStream {
             Ok(Some(c))
         } else {
             let buf = self.inner.read_string(self.buffer_size)?;
-            self.chars_iter = buf.into_chars();
+            self.chars_iter = OwnedCharsExt::into_chars(buf);
             self.chars_read_from_buf = 0;
             let oc = self.chars_iter.next();
             if oc.is_some() {