add Leiningen plugin for new proj. template

It would be beneficial to have a Leiningen plugin that would create a new clojure-turtle project with all the correct dependencies and versions.

It's one less thing that the user has to think about. Quil itself and many other projects benefit from having an associated Leiningen template for a new project.

Review the repository and Leiningen's plugin and project-template conventions first. Define the template's required dependencies and versions, then verify that it creates a usable new clojure-turtle project with those settings. The issue names no specific files or tests, so the completion checks will need to be established before implementation.

Written by the indexing model from the issue text.