[Tell me your opinion!] Support config file

[kyu08]

I think it's good idea to support config that enables to configure behavior which has file format such as yaml.
Possible settings would include the following:

• Direction of preview window(vertical / horizontal)
• Preview command(bat / cat)
• Show executed command or not
• Behavior when return key is pressed(Run the target / Just show make ${selected_target} to prompt?(I'm not sure if possible)y)
• Forcus the target executed at the last time
• etc...

Please let me know options you want! 😀
Also I welcome your feature requests!