`truncatechars` filter is buggy and unregistered
|Reported by:||timdumol||Owned by:||nobody|
|Has patch:||no||Needs documentation:|
|Needs tests:||Patch needs improvement:|
#5025 introduced a new truncatechars filter. However, the filter is not registered as a default filter, although it is documented as such. Also, there is a typo in the patch that renders the filter unusable.