std/encoding/csv: use the new Scanner

std/encoding/csv/reader.jule

@@ -84,6 +84,7 @@
 //  field`, `comma is ,`}
 
 use "std/bytes"
+use "std/bufio"
 use "std/io"
 use "std/unicode"
 use "std/unicode/utf8"
@@ -140,7 +141,7 @@ struct Reader {
 	// By default, each call to read returns newly allocated memory owned by the caller.
 	ReuseRecord: bool
 
-	s: &io::Scanner
+	s: &bufio::Scanner
 
 	// The current line being read in the CSV file.
 	numLine: int
@@ -174,7 +175,7 @@ impl Reader {
 	static fn New(mut r: io::Reader): &Reader {
 		ret &Reader{
 			Comma: ',',
-			s: io::Scanner.New(r),
+			s: bufio::Scanner.New(r),
 		}
 	}
 
@@ -240,7 +241,7 @@ impl Reader {
 		if !scan {
 			ret nil
 		}
-		mut line := self.s.Bytes()
+		mut line := self.s.Token()
 		if len(line) == 0 {
 			ret nil
 		}