feat(add-channel): require 'PRINTER' and 'NAME' arguments
feat(add-channel): add core feature, add channel on following free port

I'm using 'declare -p' feature, as suggested by geirha on #bash,
to write back all my variable. This require to *explicit the list of
variables* in the task. This is important if some refactor introduce
new variables.

For a richer file content, e.g. mixed comment and code, try:
cat > file.new << EOF
	# some comment
	$(declare -p array)
	#.some other comment
	$(declare -p other value)
EOF
style(template): typo
refactor(perms): set 'mast' as local user for operations
feat(mk): add support for comment in channels

Everything after the first '#' (dash) is considered to be part of
the comment.
chore(git): merge feat/channel-comment
feat(mk): add 'remove-channel' skeleton
feat(mk): add 'remove-channel' core feature
style(mk,list-channels): highlight channel id
feat(mk,add-channel): output user feedback on request rule
docs(mk,add-hosts): add description and @require