Re-export often-used symbols

[cortner]

e.g.

• ExtXYZ.load or ExtXYZ or a new load_xyz
• @u_str
• ACEfit

(I will keep adding to this list)

[jameskermode]

I think I can't export load because of how FileIO.jl works

EDIT: (Although that doesn't stop ACEpotentials from exporting it, I suppose)

[cortner]

I may write a wrapper load_xyz or export ExtXYZ or something else. Just want to do something so I don't have to add 20 packages for a quick script to try out something.

In 0.6 we exported too much so I just got rid of all re-exports. But now I want to bring them back - only more judiciously.

[wcwitt]

Is there an AtomsBase-type command that would work well here? I’m thinking of load_system from here: https://juliamolsim.github.io/AtomsBase.jl/dev/tutorial/

But not very familiar with AtomsIO yet.

[cortner]

I've only ever used ExtXYZ, but it would be good if we generalize

[wcwitt]

I was wondering mainly if there is an established command in that ecosystem for loading a bunch of frames. After looking more closely, it seems like AtomsIO offers load_system for single frames, as well as load_trajectory, but neither seems appropriate here.

So I'm happy with any of these options:

I may write a wrapper load_xyz or export ExtXYZ or something else