move coremem/mat -> coremem/sim/legacy/mat

crates/coremem/src/sim/mod.rs

@@ -1,5 +1,4 @@
 use crate::geom::{Coord, Cube, Index, InvertedRegion, Meters, Region};
-use crate::mat;
 use crate::types::real::Real;
 use crate::types::vec::{Vec3, Vec3u};
 use crate::stim::{AbstractStimulus, NoopStimulus};
@@ -385,7 +384,7 @@ pub trait SampleableSim: Send + Sync {
                 let cell = self.sample(idx.to_meters(self.feature_size()));
                 *e = cell.e().cast();
                 *h = cell.h().cast();
-                mat::Static {
+                legacy::mat::Static {
                     conductivity: cell.conductivity().cast(),
                     m: cell.m().cast(),
                 }