fix heat plotting, missing changelog items

CHANGELOG.md

@@ -35,6 +35,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `SubpixelSpec` accepted by `Simulation.subpixel` to select subpixel averaging methods separately for dielectric, metal, and PEC materials. Specifically, added support for conformal mesh methods near PEC structures that can be specified through the field `pec` in the `SubpixelSpec` class. Note: previously, `subpixel=False` was implementing staircasing for every material except PEC. Now, `subpixel=False` implements direct staircasing for all materials. For PEC, the behavior of `subpixel=False` in Tidy3D < 2.7 is now achieved through `subpixel=SubpixelSpec(pec=HeuristicPECStaircasing())`, while `subpixel=True` in Tidy3D < 2.7 is now achieved through `subpixel=SubpixelSpec(pec=Staircasing())`. The default is `subpixel=SubpixelSpec(pec=PECConformal())` for more accurate PEC modelling.
 - Lossless `Green2008` variant for crystalline silicon added to material library.
 - `GridSpec` supports `snapping_points` that enforce grid boundaries to pass through them.
+- Support for unstructured datasets (`TriangularGridDataset` and `TetrahedralGridDataset`) in custom medium classes.
 
 ### Changed
 - IMPORTANT NOTE: differentiable fields in the `adjoint` plugin (`JaxBox.size`, `JaxBox.center`, `JaxPolySlab.vertices`) no longer store the derivative information after the object is initialized. For example, if using JaxPolySlab.vertices directly in an objective function, the vertices will have no effect on the gradient. Instead, this information is now stored in a field of the same name with `_jax` suffix, eg. `JaxPolySlab.vertices_jax`. For some applications, such as evaluating penalty values, please change to `radius_penalty.evaluate(polyslab.vertices_jax)` or use the vertices as generated by your parameterization functions (`make_vertices(params)`).
@@ -49,6 +50,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Relax validation of smallest triangle area in `TriangleMesh`.
 - Default variant for silicon dioxide in material library switched from `Horiba` to `Palik_Lossless`.
 - Sources and monitors which are exactly at the simulation domain boundaries will now error. They can still be placed very close to the boundaries, but need to be on the inside of the region.
+- Relaxed `dt` stability criterion for 1D and 2D simulations.
 
 ### Fixed
 - Bug in PolySlab intersection if slab bounds are `inf` on one side.