Allow to specify a session configuration per project

[ngirard]

• Run cargo update
• add home_config() (intermediate step)
• Add DmuxConf trait

This is my take on #11.

The code is not perfect, but it's a starting point. I cannot afford to spend more time on it, I'm just hoping it'll be helpful.

It adds such -D | profile_from_dir option.
When -D is specified, such as

dmenu -D ~/my/project/dir

then the configuration file is expected to be found within the selected_dir path (~/my/project/dir in the above example).

The name of the config file is currently hardwired to dmux.conf.toml (did I say that the code was just a starting point...?).

Cheers !

[zdcthomas]

I really like the DmuxConf trait idea, I'll be able to look though this in more detail later today, thanks!