HMILayout Tmplits

[sanhhphan]

What:
This will allow user to create a basic hmi layout with a navigation bar, a main content area and a footer.

1. The navigation bar will have a default minimum and maximum size to start, when contents overflow, this area will expand to the maximum size declared. When the are reaches its maximum size, this area will be scrollable.
2. Main content area will have a fixed size. When content overflow, this area will be scrollable.
3. Footer is a fixed size are.
4. Users can change some of the styling, using CSS variables.

Why:
This helps making basic HMI layout faster and easier.

[sclaiborne]

Maybe we can meet up to discuss the open questions