Add 'show_all', 'hide_all' methods on top level renderjson element

[movitto]

When called, these will walk down the renderjson DOM structure and invoke 'show' and 'hide' on all the appropriate elements.

Use like so:

const rj = renderjson({ js : 'on })
document.getElementById("test").appendChild(rj);

rj.show_all();
rj.hide_all();
// ^ wire these up to a button click, etc