Convert all animations in Docs from mp4 to gifs

[navidcy]

https://fourierflows.github.io/GeophysicalFlowsDocumentation/previews/PR157/

Closes #113

[glwagner]

Love gif's! I usually use fps=8 but if you have a lot of output it makes sense to speed it up...

[navidcy]

Do you reckon the animations go fast? They look good on my screen.

[navidcy]

(The only problem with gifs is that they are bigger in file size...)

[glwagner]

I think you could decrease the number of outputs and change to fps=8 to speed up the runs, that's all.

[glwagner]

Right, so decreasing the number of snapshots and also slowing the movies down to obtain a similar effect would also reduce the file size.

[navidcy]

Well, the numbers here are the minimum that my eyes and brain feel good with. E.g., examples with stochastic forcing become too flickery...

(I did try to reduce output numbers at some point.)

But if you wanna have a go trying to reduce the numbers go for it :)

[navidcy]

Damn... you got me started now :)

[glwagner]

I think it's ok if the movies don't look "continuous". The question is not "how pretty" but "how useful", I think.

[navidcy]

as pretty as one can get! :)

[navidcy]

I'll merge now and we can work on this at some later time. Until then I'll try to keep cleaning the GeophysicalFlowsDocumentation repo.