Allow multiple Render windows, each one customizable

[Lorp]

Each Render window:

• has its own axis settings
• custom text
• typographic controls for font-size, line-height, measure, colour, line-wrap settings, custom CSS
• optionally shows untransformed font in grey layer
• option for a waterfall of sizes
• option for a waterfall of a single axis setting
• maybe a special mode that displays all Named Instances

This way paragraphs can be observed at the same time as headings.

The collection of windows should be saved in LocalStorage.