gmnhg is the new program that generates a Gemini site from Hugo site
content. It reads its input from content/, static/, and layouts/gmnhg/.
Its output by default goes to output/.
More doc is available in the program doc header.
This also introduces a simple program, md2gmn, that is meant for testing
the renderer on Markdown files. Nonetheless, it can be used as
a standalone tool as well.
