Plots update slowly when updating Sv_range frequently

[ldr426]

After changing the values several times for the Sv_range the demo stopped making any changes: most probably it queued all the options uesers give it. That made click even more which most probably made it worse

We could register only the last one. If there is a way to cancel or time out a sequence of requests it will make it better.

Originally posted by @valentina-s in #93 (review)

[leewujung]

Let's push this to after the Refactoring milestone is done and we can focus on efficiency and timeout issues, since this is likely going to be a recurrent thing for other viz types too.