Add helper method to get and linkify issue numbers

Review Request #8553 — Created Nov. 26, 2016 and discarded — Latest diff uploaded

Information

RBTools
release-0.7.x

Reviewers

The methods can be used to automatically find
issue numbers in review request description.

* linkify_ticket_refs: Make issues to a link
* get_ticket_refs: Returns issues as a set

Patch is based on work of Halvor Lund!