This commit adds it to the three places where paragraph formatting can
be applied right now (directly on the paragraph, paragraph styles, and
bullets/numbering styles). I'm separately adding an entry to the wiki
regarding what these methods do (widow/orphan control)
This change brings increased type safety to uses of
XmlAttributeComponent. Now the compiler is checkign for us that the
properties that get passed in to every subclass match the intended
interface, and also that the xmlKeys property -> xml attribute mapping
has all the right keys
