elvis 2.x is almost completely separate from 1.x.
I wrote this, my second vi clone,
because my first one inherited too many
limitations from the real vi, and from Minix.
The biggest change
is the support for multiple edit buffers and multiple windows,
neither of which could be retrofitted into 1.x very easily.
I also wanted to shed the line-length limitation, and have online
help written in HTML.