Make changes suitable so that wikilens theme (and wikilens.org) work properly.

Make changes suitable so that wikilens theme (and wikilens.org) work properly.
+ Remove predictions (for now)
+ Use new RatingsDb singleton.
+ Change RatingWidgetHtml() to use parameters like a normal PHP function
  so we can have PHP check that we're passing the right # of them.
+ Change RatingWidgetHtml() to be callable static-ally
  (without a plugin object)
+ Remove the "RateIt" button for now, because we don't use it on wikilens.org.
  Maybe if someone wants the button, there can be an arg or flag for it.
+ Always show the cancel button, because UI widgets should not hide.
+ Remove the "No opinion" button for now, because we don't yet store that.
  This is a useful thing, tho, for the future.

git-svn-id: svn://svn.code.sf.net/p/phpwiki/code/trunk@3822 96ab9672-09ca-45d6-a79d-3d69d39ca109