MPI via ImplicitGlobalGrid.jl + abstract flow and BCs#236

Draft

b-fg wants to merge 23 commits intomasterfrom

Commits on Jul 4, 2025

First version. A bug requires remeasure=true to work, needs fixing.
b-fg
committed

Commits on Dec 28, 2025

Commits on Apr 4, 2026

Working 2D version MPI
b-fg
committed

Commits on Apr 7, 2026

Working MPI 2D with new PLAN.md, simplified MPI.
b-fg
committed

Commits on Apr 8, 2026

Fixed exitBC and improves mpi_halo_update by reducing allocations.
b-fg
committed

Commits on Apr 12, 2026

Commits on Apr 13, 2026