Add support for LMS

[epoupon]

Hello,

It would be great to support password authentication for servers that are using API version <= 1.12.0
Several implementations still stick to older versions, mainly to avoid storing passwords in plain texts.
Examples:

• LMS (https://github.com/epoupon/lms)
• supysonic (https://github.com/spl0k/supysonic)

You could imagine a secure fallback to plain password method if the following conditions are met:

• first attempt returned a code 30 (Incompatible Subsonic REST protocol version. Server must upgrade.)
• the URL scheme is https

[fangfufu]

This is implemented in 0577630, you can activate the mode using --sonic-insecure. I am not a fan of automatic protocol downgrade.

[fangfufu]

By the way, to mount your LMS, you need --sonic-insecure and --no-range-check.

[epoupon]

Thanks!