`rclone obscure` currently only accepts a command line argument of `password` to generate
an obfuscated password. This is an issue since generating obfuscated passwords programatically
requires sending the plain text password as a shell argument, which can cause problems if the
password contains shell characters, or if the password is from an untrusted source.
This patch opens up STDIN which will allow developers to open the STDIN source and print a password
directly to `rclone obscure`, which can increase safety and convenince.
The purpose of this is to make it easier to maintain and eventually to
allow the rclone backends to be re-used in other projects without
having to use the rclone configuration system.
The new code layout is documented in CONTRIBUTING.
