#36 Serializer violates a SHOULD

[Colin Paul Adams]

"The HTML output method MAY output a character using a character entity reference in preference to using a numeric character reference, if an entity is defined for the character in the version of HTML that the output method is using. Entity references and character references SHOULD be used only where the character is not present in the selected encoding, or where the visual representation of the character is unclear (as with  , for example)."

This SHOULD is violated.
Also, indenting adds unnecessary newlines. Whilst this is definitely not a bug, it could be improved.