add doctype and encoding to generated HTML
add a link back to github repo

Using the standard GitHub ribbon. For the
offline (single-file) version it's included
via a data URI.
rework deps to git submodules. include jquery-ui

jQuery UI "sortable" seems perfect for this
application.

The application is now enormous (getting close
to a megabyte before minification). This is
mostly because we include _all_ of jQuery UI.

Once the project UI has stabilized, working out
which parts of jQuery UI we actually need and
omitting the rest is an absolute must.
adding some of the widgets that will be relevant
tweak size of sortable widgets to be adjustable

Should now follow text size and be more in line
with the rest of the widgets.
remove old fetch-deps script

(We switched to git submodules instead.)
include jquery UI images with data URIs

The goal is that this version should be a
completely self-contained HTMl document.
"Encode" button instead of "Hide"

"Hide" is widely understood in an UI context
(e.g. hide some sort of widget on the screen),
so it might be easy to miss that it's central
functionality.
interaction between the two sequence displays

Enter with the mouse/touch, or enter by
copy-pasting into the text box.
handle pasted sequence text directly
accept sequences not starting from zero

Be conservative for output, liberal for input.
There's no convincing reason not to do this.
One-based sequences are natural for users,
zero-based sequences are natural for code,
and in this case there's an unambiguous
correspondence between the two within any
set sequence length (which is all we're
interested in).