- use new `ModelMetadata.HtmlEncode` property in HTML helpers
- specifically in default HTML display and editor object templates (e.g.
`@Html.DisplayFor()`) when value is non-`null` and the template is invoked
with template depth greater than 1
- similar to MVC 5.2 commit [2b12791aee4f](https://aspnetwebstack.codeplex.com/SourceControl/changeset/2b12791aee4ffc56c7928b623bb45ee425813021)
nits:
- remove dupe `null` check in `DefaultDisplayTemplates.ObjectTemplate()`
- move backing fields initialized with constants together in `ModelMetadata`
- #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