Create parcats_grid_subplots mock with 4 grid-based subplots

This combines the former colorbar and font mocks. And adds a parcats
trace with a Latex category label as well.

Author: Jon M. Mease

test/image/baselines/parcats_colorbar.png

@@ -0,0 +1,55 @@
+{
+  "data": [
+    {"type": "parcats",
+      "domain": {"row": 0, "column": 0},
+      "dimensions":[
+        {"label": "One", "values": [1, 1, 2, 1, 2, 1, 1, 2, 1, 2, 3, 1, 2, 3, 1, 2, 1, 2, 1, 1]},
+        {"label": "Two", "values": ["A", "B", "A", "B", "C", "C", "A", "B", "C", "B", "C", "B", "C", "B", "C", "B", "C", "B", "A", "A"]},
+        {"label": "Three", "values": [11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11]}],
+      "bundlecolors": true,
+      "line": {
+        "color": [0, 0, 1, 1, 0, 1, 0, 0, 0, 2, 2, 2, 2, 1, 2, 1, 0, 2, 1, 2],
+        "shape": "linear",
+        "showscale": true,
+        "colorscale": "Viridis"
+      }
+    },
+    {"type": "parcats",
+      "domain": {"row": 0, "column": 1},
+      "dimensions":[
+        {"label": "One", "values": [1, 1, 2, 1, 2, 1, 1, 2, 1]},
+        {"label": "Two", "values": ["A", "B", "A", "B", "C", "C", "A", "B", "C"]},
+        {"label": "Three", "values": [11, 11, 11, 11, 11, 11, 11, 11, 11]}],
+      "labelfont": {"family": "Rockwell", "size": 20, "color": "gray"},
+      "tickfont": {"family": "Arial", "size": 10, "color": "firebrick"}
+    },
+    {"type": "parcats",
+      "domain": {"row": 1, "column": 0},
+      "tickfont": {"color": "black"},
+      "dimensions":[
+        {"label": "One", "values": [1, 1, 2, 1, 2, 1, 1, 2, 1]},
+        {"label": "Two",
+          "values": ["A", "B", "A", "B", "C", "C", "A", "B", "C"],
+          "categoryarray": ["A", "B", "C"],
+          "ticktext": ["$A^2$", "<b>Bold</b><br>and<br><i>Italic</i>", "<a href='http://www.google.com'>Link</a>"]
+        },
+        {"label": "Three", "values": [11, 11, 11, 11, 11, 11, 11, 11, 11]}]
+    },
+    {"type": "parcats",
+      "domain": {"row": 1, "column": 1},
+      "dimensions":[
+        {"label": "One", "values": [1, 1, 2, 1, 2, 1, 1, 2, 1]},
+        {"label": "Two", "values": ["A", "B", "A", "B", "C", "C", "A", "B", "C"]},
+        {"label": "Three", "values": [11, 11, 11, 11, 11, 11, 11, 11, 11]}],
+      "bundlecolors": false,
+      "line": {
+        "color": [0, 0, 1, 1, 0, 1, 0, 0, 0],
+        "shape": "hspline"
+      }
+    }
+  ],
+  "layout": {
+    "height": 602,
+    "width": 592,
+    "grid": {"rows": 2, "columns": 2}}
+}