GK kernels: to be removed when we have 3x sims running in g0
BGK prim moments: to be removed when we have BGK in g0 and wrapped in g2
moments: we could remove some of it now, but we have some moments (like the partial ones over v<0 or v>0) that are not in g0, and I think in g2 they are in the same kernel files as the regular moments.
The big items remaining in the g2 build are now:
g2 build takes ~3 min on my Mac