Feature: add zooming support to DSL

[kamidev]

Let's keep it very simple, though.
"A Turing complete DSL is considered a mortal sin"

[kamidev]

I think the basic commands for a single page layout are: flip and pan left/right/up/down and zooming in and out. Every command is a function working on a shape the user has specified (let's stay with square or romboid boxes for now).

We'll need navigation between multiple pages. Perhaps specifying page and shape everywhere is enough? The rest of the navigation could feel the same between pages, too.