Wrong transaltions in the filters header

[pawel-czarnecki]

Hello,

There is a problem with translating all the words in the filters header. The word 'By' is not being translated. The templates simply needs to be changed, like in Django's filter.html.

from
{% blocktrans with filter_title=title %}By {{ filter_title }}{% endblocktrans %}
to
{% blocktrans with filter_title=title %} By {{ filter_title }} {% endblocktrans %}

Unfold version 0.53.0

[lukasvinclav]

Please submit a PR with the fix and here is another PR which was supposed to fix the issue #1146.

PS: In the future, please don't ignore the issue template. This template helps me a lot to quickly understand the problem.