This patch does three major things:
* Merges the django.template.debug implementation into django.template.base.
* Simplifies the debug implementation.
The old implementation copied debug information to every token and node.
The django_template_source attribute was set in multiple places, some
quite hacky, like django.template.defaulttags.ForNode.
Debug information is now annotated in two high-level places:
* Template.compile_nodelist for errors during parsing
* Node.render_annotated for errors during rendering
These were chosen because they have access to the template and context
as well as to all exceptions that happen during either the parse or
render phase.
* Moves the contextual line traceback information creation from
django.views.debug into django.template.base.Template. The debug views now
only deal with the presentation of the debug information.
This test failed because a different error code is raised on Windows when
opening a directory. Since the particular message isn't as important to this
test as the fact that the original IOError is reraised, this fixes the test
by making the assertion more generic.
A deprecation path is required because the return type of
django.template.loader.get_template changed during the
multiple template engines refactor.
test_csrf_token_in_404 was incorrect: it tested the case when the
hardcoded template was rendered, and that template doesn't depend on the
CSRF token. This commit makes it test the case when a custom template is
rendered.
Passed the engine instance to loaders. This is a prerequisite for
looking up configuration on the engine instance instead of global
settings.
This is backwards incompatible for custom template loaders that override
__init__. However the documentation doesn't talk about __init__ and the
way to pass arguments to custom template loaders isn't specified. I'm
considering it a private API.
Wherever possible this filesystem path is derived automatically from the app
module's ``__path__`` and ``__file__`` attributes (this avoids any
backwards-compatibility problems).
AppConfig allows specifying an app's filesystem location explicitly, which
overrides all autodetection based on ``__path__`` and ``__file__``. This
permits Django to support any type of module as an app (namespace packages,
fake modules, modules loaded by other hypothetical non-filesystem module
loaders), as long as the app is configured with an explicit filesystem path.
Thanks Aymeric for review and discussion.
