Workspaces & Layouts

[robmoffat]

Placeholder for a discussion with @nkolba and @sebbenmbarek about how we handle layouts (Golden Layout?) and workspaces.

• We need to consider how Sail will handle multiple tabs, and how it will divide a tab into multiple apps.
• How does the user configure this? How is it persisted between sessions?
• What happens when an app opens a new window? How will this be handled?
• Display of directory "drawer" as in @sebbenmbarek's Miro designs.