Fixed recently broken gradient code
It turned out that "repeat" was already a property of String.
I renamed some variables and did minor cleanup.
Added support for invisible bonds
These are needed for balloonModelElectrons.json in [#73733104]
Images now display on bonds
Added image-on-bond.json interative as an example.
You can find it in lab-interactives-site.
It'll work when this branch is merged.
Required for [#73733104].
Merge pull request #67 from concord-consortium/invisible-bond

Added support for invisible bonds
Merge pull request #66 from concord-consortium/image-on-bond

Images now display on bonds
Merge pull request #64 from concord-consortium/gradient-fix

Fixed recently broken gradient code
Dual Sensor Connector: Default the second sensor to the second connected sensor
Add draw support for graphs

[#74566376]
Custom line colors enabled in graphs
[#74535922]
Labels for the legend now are recognized in interactive JSON
[#74536668]
Bugfixes all around.
[#74536668]
Grapher now accepts CSS colors instead of arrays
Works in the graph itself as well as in the legend.
[#74535922]
[#74536668]
Updated lab-grapher to most recent master
Merge pull request #69 from concord-consortium/graph-line-colors-legend

Graphs have customizable line colors and integrated legend
Don't even bother looking up an axis label if we're not going to use it.

This prevents errors when the labels aren't defined elsewhere (graph
with an iframe model, for instance).
Update lab-grapher to fix autoscaling when drawing
Listen to data point events from the graph
iframe phone support for getting a specific dataset
Be specific about what properties we should draw on in graphs
Support for listening and sending dataset events