Fixed #27130 -- Allow using the DjangoTemplates engine without config…

[reficul31]

…uring settings

[aaugustin]

The fix must target django.template.engine.Engine rather than django.template.backends.django.DjangoTemplates.

The former is the template engine itself, which should be usable as a standalone template engine.

The latter is a thin integration layer for configuring the former according to the project settings.

[aaugustin]

I left a comment on the ticket explaining why I don't think any changes are needed.

[reficul31]

I might be wrong but I think this make testing with the templates quicker than with the django.template.engine.Engine. Since most people don't go over the docs, by providing this feature they might be able to test their templates more quickly as by default they know that django.template.backends.django.DjangoTemplates is being used as the default backend for templates. Again I might be wrong.

[aaugustin]

Closing per ticket.