=== Design:

(define-javascript-backend NAME ROOT FILES)

FILES are relative to ROOT, which in turn is relative to the
static files path.


=== Files that need to be ported:
weblocks.js
weblocks-debug.js
dialog.js
datagrid.js
hard-coded js in src/


=== Initial portable API:
AJAX requests
Effects (simple)

History (later)


=== Misc.
Get rid of shortcut.js (?)