New feature: Pairwise interactions have access to config fspace

[LonelyCat124]

This is required for DL_MESO style interactions, along with many others.

[LonelyCat124]

Ok, so the plan is to modify in this way:

Pairwise tasks are read-only for the config (until I need more...). This means the invoke framework can ignore the accesses for their decisions for now.

For per-particle tasks - I will enable reduction and reads. The invoke framework will check if any reduction fields are used on the config, and disable merging if so.

[LonelyCat124]

Ok, so pairwise tasks already allow reads(config) so nothing needs to change for those at the moment.

The only change needed for pairwise kernels is the need to pass the config into the kernel

[LonelyCat124]

Re: per-particle tasks and invoke framework.

The invoke framework will actually check for privilege collisions between the config fields already, so I think this doesn't need to be touched since kernels of different types are never merged.

[LonelyCat124]

An implementation now is commited in the DL_MESO_IO branch. I've tested it in a simple way, however there could be issues about this in the future.

[LonelyCat124]

Pairwise need to allow reduction to the config, so need to switch to use three_region_privilege

[LonelyCat124]

I have an implementation of this (To be tested) for 3D periodic symmetric pairwise.

[LonelyCat124]

This is implemented in the dl_meso branch now.