Duplicated code in control panels

[samreid]

Discovered during #14, I saw similar code duplicated between StandardFormGraphControlPanel.js and VertexFormGraphControlPanel.js. Here is a graphical depiction of the similarity:

I'm sure it was easier to develop as a separate copy (especially while the simulation was still under design), but now that we are preparing the simulation for long-term maintainability, perhaps it would be better to unify. For example, if we change the tandem for equationsCheckbox, it would need to be done in 4 places. Or if we decide that the axisOfSymmetryCheckbox should precede the vertexCheckbox (for all screens), that would need to be done in 3 places. Yes, the current implementation has the flexibility that if we need to put the vertexCheckbox before on one screen and after on another screen it would be very easy, but it seems much more likely that we would want to constrain this layout by design. If we end up deciding to leave the duplicated code, then I recommend to put comments at each site of duplication that indicate what the duplication is, and what other code likely needs to remain synchronized with the code in question.

Note that I'm not advocating to always eliminate 100% of duplicated code (in some cases it is appropriate to duplicate code), but just to eliminate duplication in places where it is straightforward and beneficial to eliminate. For instance, if there was a file js/common/view/GQControlPanel.js which had an option showRootsCheckbox, it could easily accommodate both of these use cases and productively constrain them to have the same behavior.

[pixelzoom]

I mentioned this in #55 (comment), and we've had this specific discussion about what is appropriate to duplicate in this sim. As the responsible developer, I've decided to prefer clarity/maintainability at the expense of some duplication that was a non-issue during implementation (and actually made it easier to respond to change requests). So I'm not going to change this. Closing.