Frontpage animations

On the frontpage, we discussed that long-term we want first two feature images, namely:
(1) animation that builds the workflow and
(2) anamation that selects in the HC widget and then selections in T-SNE change

We already agreed on the workflow a year ago. Notice that, on the current page, the widgets in "Interactive visualizations" are the same as in "Visual programming"

Start by reviewing the frontpage and comparing the widgets in “Interactive visualizations” with those in “Visual programming.” The issue describes two desired animations: building the workflow, and selecting in the HC widget so selections change in T-SNE; the work is done when both are implemented as agreed.

Written by the indexing model from the issue text.