Summary:
As it has been part of Plasma4, is mentioned in documentation still
and also all the time covered by translation system, someone out there
might perhaps still be happy to use it once in a while also with Plasma5.
Port has been straightforward, so no regressions expected.

Test Plan:
Entering "#hexdigits" works as advertized.
Changing trigger word in config UI and using new instead works as well.

Reviewers: broulik, jriddell, davidedmundson

Reviewed By: davidedmundson

Subscribers: davidedmundson, plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D10104