FR: Reorder Matrix View in V4

[kazerniel]

Related to #224

Is your feature request related to a problem? Please describe.

In V3 it was possible to set a custom order to how relationship types are displayed in Matrix view. This seem to have been removed in V4, and I'd like if it was reintroduced, as the default ordering is quite suboptimal for my use.

Describe the solution you'd like

Same functionality as V3.

Describe alternatives you've considered

I tried reordering the fields in the defining menu, but it doesn't seem to change the displayed order.