templatefuncs: use evaldate() where seems appropriate This means date("today") is allowed. Also fixes evaldate() to forcibly use the custom error message if specified.

templater: factor out function that parses argument as date tuple

templatefilters: declare input type as bytes where appropriate Some test outputs changed since input is now coerced to a byte string. I think that's okay. Maybe {date} should have some readable representation?

templatefilters: allow declaration of input data type Currently filters take an unwrapped value, which should have no hybrid magic but actually it does because stringify() relies on it. The 'intype' allows us to pre-process the magic by .e.g. evalstring() keeping filter functions as simple as they are now. stringify() is ported as an example. More follow.