Fetching only saved items

[ksykes]

Is your feature request related to a problem? Please describe.
Many people use Slack's save feature to organize messages.

Describe the solution you'd like
Implement the ability to export only saved items (messages, replies, attachments). Slack's export includes "is_starred": true, for saved items. A similar feature would be really helpful, and/or the ability to export only saved messages to one file.

[rusq]

Hey @ksykes, thanks for the suggestion, there's an issue like that already, please see #128

[rusq]

copypasterised the message to #128