Modified change list default sort

[Joshua Russo]

I've tweaked the change list sort handling so that by default it uses the full list of sort columns defined in the model. It sets all of the
headers as unselected and then behaves as it currently does if someone selects a header column to sort by. I've also modified the template to
add a Reset sort (or conditionally Reset sort and filter) button to bring everything back to the original state.

[Joshua Russo]

From \contrib\admin\views

[Joshua Russo]

From \contrib\admin\templatetags

[Joshua Russo]

From \contrib\admin\templates\admin - Added the Reset button

[Alex Gaynor]

Please provide one diff from the root of the django tree.

[Adam Vandenberg]

"if cl.order_field != None..." should be "if cl.order_field is not None..."

[dc]

Better have two separate messages for i18n than creating message from chunks

<li><a href=".">
    {% if cl.has_filters or cl.date_hierarchy %}
        {% trans 'Reset sorting and filters' %}
    {% else %}
        {% trans 'Reset sorting' %}
    {% endif %}
</a></li>

[Joshua Russo]

I've updated the code as suggested in the comments provided. (Diff done from root, IF statement fixed, and Trans split into 2 full phases)

[Joshua Russo]

with testing and docs

[Joshua Russo]

Well I have all of the regression testing and docs added, but my upload doesn't seem to be working. It reports the correct file size but doesn't display the file when I click the file name after upload.

I also found and fixed a small bug in another of the admin_views tests.

[Joshua Russo]

Trying upload without replace

[James Bennett]

1.2 is feature-frozen, moving this feature request off the milestone.

[Julien Phalip]

Closing as a duplicate of #11868 which, although newer, suggests a better approach UI-wise.