`Writer` writes fields as plural but SWIFT expects ICs with singular for some fields

[kyleaoman]

For example SWIFT apparently can't read the output of the Writer as ICs because it contains SmoothingLengths but expected SmoothingLength. This seems to be the case for Density/ies and InternalEnergy/ies as well.

Not sure whether this should be fixed in the Writer or whether SWIFT should be more flexible about what it expects in ICs? @MatthieuSchaller

[kyleaoman]

After a chat with @MatthieuSchaller the Writer should just write swift-compatible ICs. I guess we can decide whether swiftsimio should be able to read the output of the Writer, "no" might be an acceptable answer.

Some care will be needed to write everything correctly. The names are easy to fix, but there are some possible pitfalls e.g. internal energies are physical, even if coordinates are comoving.

(Writer not to be confused with the subset_writer, which we briefly were during conversation earlier.)

[JBorrow]

That's weird, this convention must have changed at some point. Obviously at some point Writer wrote ICs that worked with SWIFT.