templatefilters: raise ProgrammingError if unencodable type passed to json() This shouldn't happen for any template data types (though I know it does because of some templater bugs.) Let's clarify it is a bug.

templatefilters: handle TypeError by count() Prepares for removing the weird exception catcher from runfilter().

keyword: declare input type of date filters as date Dropped redundant dateutil.parsedate(), which is now handled by the templater.

templatefilters: declare input type as date where appropriate I'm not sure if the templateutil.date type can be a thing. Currently it's just a constant.