lib: expose `Host.Ssh.{scp_push,scp_pull}`
lib: add `EDSL.Program.copy_files`
lib: add aggressiveness to `deamonize` killing
lib: add function `Ketrew.EDSL.Program.chain`
lib: add “starting-timeout” to `Daemonize`
lib: fix extension used in `view_in_dollar_editor`
lib: allow user to cancel `State.call_query`
lib: add some visual feedback in `interact`
doc: update `README.md` and `development.md`
lib: add field `add_ssh_options` to `Host.t`
test: add a `run_ketrew_on_vagrant` in `cli.ml`

It is workflow that installs ketrew in a vagrant VM.
It can still be improved.