bacon --prefs only works in rust project.

[SebastianJL]

I usually use nvim $(bacon --prefs) to configure bacon. I just found out that bacon needs to be run in a rust project. This makes sense I guess for most other commands but it would be nice if given the --prefs option this would work from anywhere on the system. The exact error is as follows:

$ bacon --prefs
Error: Cargo.toml file not found.
bacon must be launched 
* in a rust project directory
* or with a rust project directory given in argument
(a rust project directory contains a Cargo.toml file or has such parent)

If anyone can give me some pointers or the OK that this is a change that is desired I'll try and implement it myself.