add option to not save DNADesign in localStorage on every edit

[dave-doty]

On large designs (e.g., 25,000 strands), this causes a significant slowdown.

Here's the Chrome profiler on creating a nick in such a design:

Here's the same thing with writing to localStorage disabled:

As you can see, it adds about a 0.9 second delay.

[rishabhmudradi]

Should this feature be added under 'Edit' in the top menu?

[dave-doty]

Let's put it under "File".

Note that this will require messing with the local_storage "middleware". Let me know if you want to chat about how that works.

[rishabhmudradi]

I think a short conversation might be helpful for me, I'm free anytime after 2 at your convenience.

[dave-doty]

Closed in a8bf5cd