allow cell names as top-level variables regardless of type #72

In Observable 1.x any cell could be given a name, and this name would immediately operate as a top level constant. This no longer holds for 2.0.

In 1.x the cell name also became the (id?/name?) attribute of its HTML rendering. This allowed an elegant way to:

• operate on the value of any cell that was, effectively, an HTML Element: e.g. [cellName].innerText
• and also had the side benefit of providing anchors for links across documents: @[notebookName]#[cellName] gave automatic browser navigation to a cell.

Many of my notebooks are broken by this in Observable 2.0 so I am noting this issue as a bug. But I'd also love to see it carried it over and supported as a feature which recognizes the equal status of text-as-data, especially when using the actual text (as-data) of the notebooks that you are reading is so much in the spirit of the Literate Programming that Observable champions.

BTW, I love what you are doing with Observable Notebooks 2.0.