Allow to modify sub-sections via python fields.
We want to extend the metainfo to allow something like this:
parent.energy_total = Energy(value=1.0)
This would replace:
This would be possible, but its quite some work to make it work with repeating sub-sections. Here you want something like:
Remember that we need to hook into the process and modify both parent and sub-section. To implement this, python properties are not enough, because for repeating sub-sections we need a special metainfo list class to hook into append (and other modifying methods). Possible, but quite some work.