Change Tracer->tracer in particle attribute (convention)

Author: fluidnumericsJoe

docs/user_guide/examples/tutorial_interpolation.ipynb

@@ -324,7 +324,7 @@
    "outputs": [],
    "source": [
     "SampleParticle = parcels.Particle.add_variable(\n",
-    "    parcels.Variable(\"Tracer\", dtype=np.float32, initial=np.nan)\n",
+    "    parcels.Variable(\"tracer\", dtype=np.float32, initial=np.nan)\n",
     ")\n",
     "\n",
     "\n",
@@ -420,7 +420,7 @@
     "ax[0].scatter(\n",
     "    pset[\"node\"].lon,\n",
     "    pset[\"node\"].lat,\n",
-    "    c=pset[\"node\"].Tracer,\n",
+    "    c=pset[\"node\"].tracer,\n",
     "    cmap=\"viridis\",\n",
     "    edgecolors=\"k\",\n",
     "    s=50,\n",
@@ -459,7 +459,7 @@
     "ax[1].scatter(\n",
     "    pset[\"face\"].lon,\n",
     "    pset[\"face\"].lat,\n",
-    "    c=pset[\"face\"].Tracer,\n",
+    "    c=pset[\"face\"].tracer,\n",
     "    cmap=\"viridis\",\n",
     "    edgecolors=\"k\",\n",
     "    s=50,\n",