templates: deprecate NewParse()

It it just a chain of `New("sometag").Parse(...)`, and most of our
uses don't use a tag for the template, so can call Parse.

There's no public users of this function, but deprecating it first
just in case.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

cli/command/container/list.go

@@ -82,7 +82,7 @@ func buildContainerListOptions(options *psOptions) (*container.ListOptions, erro
 
 	// always validate template when `--format` is used, for consistency
 	if len(options.format) > 0 {
-		tmpl, err := templates.NewParse("", options.format)
+		tmpl, err := templates.Parse(options.format)
 		if err != nil {
 			return nil, errors.Wrap(err, "failed to parse template")
 		}