Removed test for migration check forgotten in 7e941ba67ceab8a74ba50509d13ed4298f8305cd.
Fixed #21951 -- Updated docs to use __str__ for Python 3

Thanks Tim Graham for the report and recommendations
Fixed #21064 -- Refactored common logic in ModelAdmin.add_view and change_view.
Fixed #19496 -- Added truncatechars_html filter.

Thanks esevece for the suggestion and  Nick Sandford and Martin Warne
for the inital work on the patch.
Fixed a link in the 1.7 release notes.
Fixed a typo (I guess).
Removed _actions_icnt declaration from local scope in admin JS.

Commit 4523fcd introduces _actions_icnt to the local scope,
which overrides the value set in the HTML.

The admin would incorrectly show selected rows in a change list
as "1 of undefined selected".