Create a standalone chart viewer app

[vojtamolda]

When a matplotlib chart is created in Python REPL, the .show() function displays the figure in nice, small window. The GUI of the app looks like this:

It would be nice to provide a similar user experience if one calls the .show() method of a Plotly figure in a Swift REPL. Current implementation shows a HTML document in a browser window. This gets us 80% of the features for a very little development cost but it's still worth looking at other options.

Replacing the browser with a stand-alone app with an embedded browser view give us more flexibility and the possibility to develop features custom tailored to plotting:

• Natural export to different formats (i.e. PNG, PDF, HTML, JSON, ...) via File -> Save As... or a share button.

• Plotly modebar that is normally part of the figure and looks like this:
  
  Can be moved to native toolbar similar to this:
  

• We could display a sidebar that shows the JSON representation of the Figure.

[vojtamolda]

Here's a preliminary wireframe sketch (sorry, I'm not really good at this) that demonstrates the idea: