URL resolution logic, clean/check, shell completions

URL resolution logic, clean/check, shell completions

generate script generates from scratch
gen docs with shell not python

show all files (not just top-level dirs) in clean
update install.sh (automate completion installs)

fix installer logic test
remove `--check` flag in favor of `check` command
remove redundant `--help` argument on subcommands

more helpful warning (not error) message; clean msg
strip gcrypt:: & report URLs like git.
don't clean non-gcrypt URLs
clean URLs filtered specially for rsync:// protocol

update/fix clean command for sft/rclone