Refactor encoding to use *string instead of string as input

I don't want to clone the whole input string

encoding/ascii.go

@@ -4,8 +4,9 @@ import "bytes"
 
 type ASCIICoder struct{}
 
-func (c *ASCIICoder) Encode(s string, buf *bytes.Buffer) error {
-	buf.WriteString(s)
+func (c *ASCIICoder) Encode(s *string, buf *bytes.Buffer) error {
+	// These should be ASCII but UTF8 is a superset of ASCII so hopefully this'll be fine
+	buf.WriteString(*s)
 	return nil
 }