Images inserted using the new WYSIWYG editor cause exceptions in the PDF/RTF export

Because the xhtml2fo xslt simply explodes the style attribute into property="value" attributes, and not all the css properties are valid xsl-fo attributes. Specifically, 'display' doesn't exist (instead there are several elements corresponding to each display type), 'float' can only be used on the fo:float element, 'clear' is only valid on block elements (and a few rarely used elements), 'cursor', 'quotes', 'list-*', and 'outline-*' don't exist at all.