Parse parameter and changelog entry descriptions with markdown as prescribed by the standard.

Introduces a new `format_description()` function and relies on a new `line()` method introduced in Parsedown v1.0.0. Bumps Parsedown dependency to v1.1.4
Spaces spaces, we don't need no spaces.
Update composer.lock file.
Use v1.1 for updating the Parsedown dependency instead of v1.1.4.
Merge pull request #146 from DrewAPicture/markdown

Parse parameter and changelog entry descriptions with markdown.