html-parser supports only a few entities

[John Foerch]

The html-parser egg supports only a few entities ( , < and friends) by default. If one wants to parse html that contains other entities than these, one cannot use the simple html->sxml, but must use make-html-parser just to add entities. I propose that for purposes of html->sxml, html-parser should not validate entities at all, but simply create sxml entity forms for whatever entities it encounters.