- #965
- test call-throughs from `Html.Editor[For]()` to inner `IHtmlHelper`
- add another parameter to `DefaultTemplatesUtilities.GetHtmlHelper()`
nit: reorder dictionaries at the top of `TemplateRenderer` slightly
- focus on affect of `ModelMetadata.HasNonDefaultEditFormat` and
`IHtmlHelper.Html5DateRenderingMode`
- work through `TemplateRenderer` because individual templates only do
formatting in a few cases
- XML comments for changed `TemplateInfo` properties
- correct `DefaultDisplayTemplateTests` and `DefaultEditorTemplateTests` namespaces
- add a couple of low-level `TemplateInfo` tests
- add more `DefaultTemplatesUtilities.GetHtmlHelper()` overloads, all
returning a strongly-typed helper
- also correct that method to ensure template helpers each get a unique
`IHtmlHelper` instance