Some more cleanups, especially tests

tests/test_simulation_result.py

@@ -0,0 +1,17 @@
+from pathlib import Path
+
+import numpy as np
+
+from scgenerator.solver import SimulationResult
+
+
+def test_load_save(tmp_path: Path):
+    sim = SimulationResult(
+        np.random.randint(0, 20, (5, 5)), dict(a=[], b=[1, 2, 3], z=list(range(32)))
+    )
+    sim.save(tmp_path / "mysim")
+    sim2 = SimulationResult.load(tmp_path / "mysim.zip")
+    assert np.all(sim2.spectra == sim.spectra)
+    assert np.all(sim2.z == sim.z)
+    for k, v in sim.stats.items():
+        assert sim2.stats[k] == v