This commit fixes a small bug in the
settings/muted-topics pane.
When there are zero muted topics, the
"You have not muted any topics yet." message
was not shown.
This is fixed by adding the `required-text`
class to the table body.
The bug was introduced in 3bc818b9f7.
The set_up_muted_topics_ui and templates have been
refactored to use list_render.
This is done to support filtering and sorting of
the muted stream topics.
This also includes the addition of a new Date muted header.
Abhijeet Prasad Bodas
Rohitt Vashishtha
Ryan Rehman
Anders Kaseorg