Add square logos for Nengo GUI.

[jgosmann]

We should replace the Nengo GUI favicon with the actual Nengo logo. This PR adds square icons for Nengo GUI. I chose pink (#ff007e) as color, but I'm open to other suggestions.

[jgosmann]

@tcstewar

[jgosmann]

ping @tcstewar

[tcstewar]

ping @tcstewar

Thank you for the reminder!

And I am so the wrong person to pick colours. :) I like pink, so I'm happy with it, but I also have learned from previous experience that my colour preferences are questionable.... ;) The only other thing that comes to mind is one of the blues that are currently used in nengo gui (either the plot colour for the first value in a value plot, or the timeslider background colour, or the build-progress bar). But if the pink doesn't clash horribly with any of those, I'm happy sticking with it!

[celiasmith]

I'd love to see it in the first plot blue, too! (Or any of the others, just guessing I'll find that the most appealing :) )

[jgosmann]

Here are the logos with blue:

Pink is more salient which makes the browser tab for the GUI easier to find (between maybe multiple tabs with a similar logo for documentation).

[jgosmann]

Can we come to a decision on the Nengo GUI logo? (I'd like to do an official release of the Jupyter Lab plugin which uses the logo as icon.) Maybe do a poll with emoji reactions?

[celiasmith]

I like the blue one :)

[tcstewar]

I'm not allowed to vote given my colour vision, so I'll run the poll. We seem to have two options: pink and blue. So blue will be the thumbs-up icon 👍 , and pink is the heart icon ❤️ . Respond to this post with your vote!

[p3jawors]

One thing to keep in mind is that we are already using blue for both the Nengo Loihi and Nengo SpiNNaker logos. Yellow would be another option to pink that we haven't used yet, and it would pop in the same way.