Updating unitconverters notebook to use Unity

Author: erikvansebille

docs/user_guide/examples/tutorial_unitconverters.ipynb

@@ -146,7 +146,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "So the U field has a `GeographicPolar` UnitConverter object, the V field has a `Geographic` UnitConverter and the `temp` field has a `UnitConverter` object.\n",
+    "So the U field has a `GeographicPolar` UnitConverter object, the V field has a `Geographic` UnitConverter and the `temp` field has a `Unity` object.\n",
     "\n",
     "Indeed, if we multiply the value of the V field with 1852 \\* 60 (the number of meters in 1 degree of latitude), we get the expected 1 m/s.\n"
    ]
@@ -248,7 +248,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "Indeed, in this case all Fields have the same default `UnitConverter` object.\n"
+    "Indeed, in this case all Fields have the same default `Unity` object.\n"
    ]
   },
   {
@@ -348,7 +348,7 @@
     "| `\"V\"`              | `Geographic`            | $1852 \\cdot 60$                                           | 1                            |\n",
     "| `\"Kh_zonal\"`       | `GeographicPolarSquare` | $(1852 \\cdot 60 \\cdot \\cos(lat \\cdot \\frac{\\pi}{180}))^2$ | 1                            |\n",
     "| `\"Kh_meridional\"`  | `GeographicSquare`      | $(1852 \\cdot 60)^2$                                       | 1                            |\n",
-    "| All other fields   | `UnitConverter`         | 1                                                         | 1                            |\n",
+    "| All other fields   | `Unity`                 | 1                                                         | 1                            |\n",
     "\n",
     "Only four Field names are recognised and assigned an automatic UnitConverter object. This means that things might go very wrong when e.g. a velocity field is not called `U` or `V`.\n",
     "\n",