Add visibility annotations

[aaronsamuel137]

In https://github.com/phetsims/tasks/issues/307 we decided that developers should add these to their own sims.

Consensus: we will leave it up to developers whether to keep things up to date (a) as we go (b) as the sim is republished or (c) before a developer leaves the team.

Since I am about to be leaving, I will try to get this done for color-vision before hand.

[aaronsamuel137]

As part of these changes, I turned some attributes into vars that didn't really need to be attributes. However, now I am wondering whether these were needed for together somehow.

Here's the attributes I changed to vars:

In ColorVisionScreenView:

• resetAllButton
• playPauseButton
• stepButton

In RGBModel:

• redEventModel
• greenEventModel
• blueEventModel

In GaussianWavelengthSlider:

• slider

Partly wondering this, because I see this in RGBSlider:

    // @public but only for together.js
    this.slider = hSlider;

Can @samreid or @jbphet comment, since they worked on instrumenting this sim.

[samreid]

No need to make things instance properties, tandem handles closure vars nicely. Also, color vision is already instrumented and seems to be working nicely as well. I removed the this.slider line and the sim runs without problems and I don't expect any together or phet-io issues.

[samreid]

Removed above, closing.