Remove proton/neutron Number

[RemiLehe]

This removes the proton/neutron number from the ED-PIC extension, since it is now possible to specify it with SpeciesType.

Implements issue: Close #191

Affected Components

• EXT_ED-PIC

Logic Changes

Expressing ions in ED-PIC can now be done by using the SpeciesType extension.

Writer Changes

Data writers that were writing the proton/neutron number should now use the SpeciesType extension.

This might require a lookup of an element name in the periodic table for the naming. Previously, one could just define two numbers without knowing how an ion/isotope is abbreviated in the periodic table.

Reader Changes

I am not aware of any reader that currently checks this attribute, but in theory data readers should now look at the SpeciesType information.

• [x] openPMD-validator: remove check in ED-PIC https://github.com/openPMD/openPMD-validator/pull/39

Data Converter

Data converters should switch to using the SpeciesType.

• [ ] https://github.com/openPMD/openPMD-updater

[ax3l]

I am not aware of any reader that currently checks this attribute

We do in manual post-processing from time to time.

Does the openPMD validator check the proton number?

Yes, it does check its type. We need to remove these two lines: https://github.com/openPMD/openPMD-validator/pull/39

Data converters should switch to using the SpeciesType.

I would like to hold this PR until we have a data converter PR for it. This way of working we will only merge changes to the standard that we can also convert to :)

(The data conversion will need to implement a periodic table lookup, that's fun! :-p )