Make it possible for template loaders to optionally return compiled Template object

[redvasily]

Django now uses two stage template loading process:

This patch follows our (very) small discussion on mailing list: ​http://groups.google.ru/group/django-developers/browse_thread/thread/5e54ab5cac98da90?hl=en

1. First find_template_source() which uses settings.TEMPLATE_LOADERS to actually load template
2. get_template_from_string() which is essentially a factory function for Template objects

I modified django.template.loader.find_template_source() function and renamed it to find_template() to check if return value of template loader is a tuple - if it's a tuple than standard it proceeds with standard template loading process:

origin = make_origin(display_name, loader, name, dirs)
template = Template(template, origin, name)

But if it fails to unpack return value of template loader it assumes that template loader returned compiled template object and returns it.

This change is backwards compatible and opens a lot of new possibilities for template system.

[redvasily]

Diff implementing this ticket