Feature idea: Parameterized macros (or, "smart replacements")

The thing I’d really like to avoid is to have to pre-define all of the possible options — like, if someone makes a new chat room for home-automation, I don’t want someone to have to manually add it… I’d just like {chat:home-automation} to generate [Fedora Chat: #home-automation](https://matrix.to/#/#home-automtaion:fedoraproject.org).