Merge pull request #834 from vdboor/issue_19906_list_classes

from django.utils import formats

from django.utils.html import format_html

from django.utils.safestring import mark_safe

from django.utils import six

from django.utils.text import capfirst

from django.utils.translation import ugettext as _

from django.utils.encoding import smart_text, force_text

from django.utils.encoding import force_text

from django.template import Library

from django.template.loader import get_template

from django.template.context import Context

                # Not sortable

                yield {

                    "text": text,

                    "class_attrib": format_html(' class="column-{0}"', field_name),

                    "sortable": False,

                }

                continue

        # OK, it is sortable if we got this far

        th_classes = ['sortable']

        th_classes = ['sortable', 'column-{0}'.format(field_name)]

        order_type = ''

        new_order_type = 'asc'

        sort_priority = 0

      The above will tell Django to order by the ``first_name`` field when

      trying to sort by ``colored_first_name`` in the admin.

    * .. versionadded:: 1.6

      The field names in ``list_display`` will also appear as CSS classes in

      the HTML output, in the form of ``column-<field_name>`` on each ``<th>``

      element. This can be used to set column widths in a CSS file for example.

.. attribute:: ModelAdmin.list_display_links

    Set ``list_display_links`` to control which fields in ``list_display``

  context through to feed templates using a new `Feed.get_context_data()`

  callback.

* The admin list columns have a ``column-<field_name>`` class in the HTML

  so the columns header can be styled with CSS, e.g. to set a column width.

Backwards incompatible changes in 1.6

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