when chiseling a sphere out of hcp lattice rMin/rMax now mean the limits of the spherical domain, not the min/max node coordinate. this makes it easier for a client to build concentric shells.
switching the name of the cutoff density (0.94 following melosh) to etamin_solid, to avoid clash with spheral's etamin which is an underflow protection. also temporarily reverting the hcp sphere carving to test the effects in isolation."