[feature request] Import/export settings

[KaKooDa]

The ability to import and exporting our white and blacklists is really helpful. This way we can share our lists to decrease the burden of checking each java-script file individually. Also it helps to reproduce our settings when migrating to a new system. Addons such as LeechBlockNG (free software) already provide this. So can it be merged into LibreJS? Thanks.