Adding range tests

@knolleary, @dceejay , here's my intended change to the "range" node. I'd rename it as "scale". I also extended the HTML docs and added the first two sample unit tests.

(Even the icon is more like a "scale" operation in graphics, rather than some kind of range... The question is: would people dislike the renaming/regression? I think if it's documented in say release notes then it's OK. Thoughts?)

If you're happy with this, it will be a breeze to write all the required unit tests, based on the <code>genericScaleTest</code>


such as:

<code>
    it('scales numbers down such as centimetres to metres', function(done) {
        genericScaleTest("scale", 0, 100, 0, 1, false, 55, 0.55, done);
    });
</code>


Thoughts? Thanks!