RFC: let's make ultimate meta packages for physics

[Roger-luo]

I find sometimes I just want to type one command using MyUltimateModule and then all the common things for my daily work will be imported, and I don't need to look up some doc online then find which package is that function come from. e.g it might be pretty hard to notice something like multithreaded broadcast actually exists in Strided.jl (JuliaLang/julia#19777) and you can actually find fast expv function in ExponentialUtilities, all these are very basic things that used by physicists almost everyday.

And I find I also keep getting complains about finding functions from packages, it is good to be modular, but it is also convenient (especially for beginners) to have an ultimate module exports a lot things. e.g statistics community has https://github.com/JuliaStats/StatsKit.jl

Thus, instead of just pointing out what kind of packages are out there on our website, it could be useful to make several ultimate packages that classifies concrete packages by categories and point out what it contains on the website (which is the current guide). When a user become a develop, this will also be a convenient guide for them to find which package to contribute.