Dumping screen to file (feature request)

As discussed elsewhere, Nail could dump the visible portion of the current buffer to a text file. The output ought to resemble the actual view on screen as much as possible. It probably isn't necessary to be too realistic about drawing exactly the same border, status bar etc, as long as the content is correct and falls into the correct columns and rows. Possible output approaches:

1. literal echoes, line by line, of the text content in the visible screen.
2. as (1) but with colour escape codes (even possible in a text file?)
3. as above but wrapped in an html 'pre' or 'code' element. I guess this could be run through a syntax highlighting prettifier after the event by the user?

Might it also be useful to insert a short preamble that notes the name of the binary file, date/time of dump, etc?

No file, test, or entry point is identified. First clarify whether the dump should be plain text, ANSI-colored text, or HTML, and whether metadata is required. Done should mean that the chosen format faithfully represents the visible buffer content in the correct rows and columns.

Written by the indexing model from the issue text.