Add new port for Silq

Silq is a high-level programming language for quantum computing with a
strong static type system.

The compiler is accompanied by a large collection of example files, some of
them implementing solutions to Microsoft's Q# Summer 2018 and Winter 2019
coding contest on Codeforces.

The port version is based on the date of the latest commit to the project
repository, aince there have been no regular releases, yet. (Only one tag
has been created to mark the state presented on a conference.)

Approved by: antoine (mentor)