~chambln/cosine.blue

ref: c2ea1b3b7747ea057db06d34ef2f5c21b03f053e cosine.blue/.builds d---------
Add imagemagick to debian build spec
Deploy only master branch
Use Debian stable for lint, build, deploy tasks
deploy: Add cosine.blue as a known host
Hard-code cmark for markup and fix build manifest
lint: Have shellcheck follow source statements
Add build manifest with tasks: lint, build, deploy