review for color-blindness accessibility

[pixelzoom]

Related to #2 (code review):

-[ ] Is PhetColorScheme used where appropriate? Verify that the sim is not inventing/creating its own colors for things that have been standardized in PhetColorScheme. Identify any colors that might be worth adding to PhetColorScheme.

SpringNodes.js and NormalModesIconFactory.js currently use stroke: 'red'. Should they be using PhetColorScheme.RED_COLORBLIND?

[Hyodar]

Replaced both of them to RED_COLORBLIND. Closing the issue, if necessary reopen it.

[pixelzoom]

Reopening. Sorry that I wasn't clear on this one. Colors are typically reviewed by a sim designer, to check for color-blindness accessibility. And the possible use of PhetColorScheme.RED_COLORBLIND was just one example. So before you do anything else, a sim designer will review and (possibly) request color changes.

[Hyodar]

No problem! We'll be waiting for your review.

[DianaTavares]

We have an updated version of the mockup for this simulation. I test for colorblind and looks like to colors we are using are appropriate. All the components in the sim can be recognized well.

Closing this issue.