Openpmd format for Ocelot tracking code

[zhangli28]

Dear Developers,

I recent came to know that the particle tracking code OCELOT can read openpmd data format (https://github.com/ocelot-collab/ocelot/commit/55d485d19ab7e9c3e92c09484588aa85b35a7a13).

This is a nice combination of PIC and then tracking of particles in beam line.

I am wonder if you have ever tried to use FBPIC or WarpX output data file to read in Ocelot ?

This may be interesting for many users.

Thanks.