Improved tutorial

Create a tutorial that also supports the zoom functionality:

* When user goes to the tutorial, there's a short explanation of the tutorial and how to start it. Something like:
"Welcome to our tutorial. You will learn how to read graphs using speech, tones and braille.
Let's start with moving your finger across your braille display. You should feel...
On the right is the zoom area, which currently shows...
Now, let's zoom on the next value. Please press the right arrow."

Then, if user presses anything else:
"Please press the right arrow"

If user presses the right arrow:
"Now move your finger across the right area. Do you feel is changed to be longer? That's because the value is..."

etc.

That's the general idea.

As discussed, it would be easiest to add triggers to the tutorial into the current js events. If that doesn't work out, we can consider a separate page.