Tabs (like a web browser)

[NickGeek]

Is your feature request related to a problem? Please describe.
I'd like to be able to quickly switch between two notes at the same time (and even better, notes across notebooks). Having some sort of tabbed system so I can have more than one note open at the same time would be awesome.

Describe the solution you'd like
Something like a plus button on the breadcrumb bar to open a new micropad view.

Additional context
To make it a less massive change to the structure of the application state, each tab could have its own unique Store with some IPC-style communication for shared state like if the same notebook is open in two tabs.