Added jinja2 template backend.
Added Django template backend.
Looked up the default template engine in the list of all engines.
Removed private API django.template.loader.find_template.
Removed some uses of global APIs from django.template.loader.
Supported multiple template engines in get_template and select_template.
Added support for explicitly selecting an engine.
Removed private API get_template_from_string.
Removed extraneous arguments in Engine.get_template_from_string.

This aligns the Django Template Engine API with the common template
backend API.
Passed a reference to the current engine when instanciating Template.
Renamed get_template_from_string to from_string.

The shorter name is just as explicit and, well, shorter.
Supported multiple template engines in render_to_string.

Adjusted its API through a deprecation path according to the DEP.
Added a comment about the last use of Engine.get_default().