Animations speed-up

[OlehKSS]

For showing activation data on the cortex it is required to perform data up-sampling. Earlier it was done once and for all moments of time specified. However, up-sampled activation data can occupy a lot of memory, so those calculations were moved to Python side and now are performed upon request from JavaScript. It is done through server and significantly slows animation. Find a way how to speed-up those calculations and reduce time that is taken by frame changes.