split axesAttrs inheritence for title.text and title.font

... so that we can add other `title.*` to cartesian axes
    w/o breaking other subplots

Author: etpinard

src/plots/gl3d/layout/axis_attributes.js

@@ -71,7 +71,10 @@ module.exports = overrideAll({
     color: axesAttrs.color,
     categoryorder: axesAttrs.categoryorder,
     categoryarray: axesAttrs.categoryarray,
-    title: axesAttrs.title,
+    title: {
+        text: axesAttrs.title.text,
+        font: axesAttrs.title.font
+    },
     type: extendFlat({}, axesAttrs.type, {
         values: ['-', 'linear', 'log', 'date', 'category']
     }),

src/plots/polar/layout_attributes.js

@@ -114,8 +114,17 @@ var radialAxisAttrs = {
     },
 
 
-    title: overrideAll(axesAttrs.title, 'plot', 'from-root'),
-    // might need a 'titleside' and even 'titledirection' down the road
+    title: {
+        // radial title is not gui-editable at the moment,
+        // so it needs dflt: '', similar to carpet axes.
+        text: extendFlat({}, axesAttrs.title.text, {editType: 'plot', dflt: ''}),
+        font: extendFlat({}, axesAttrs.title.font, {editType: 'plot'}),
+
+        // TODO
+        // - might need a 'titleside' and even 'titledirection' down the road
+
+        editType: 'plot'
+    },
 
     hoverformat: axesAttrs.hoverformat,
 
@@ -138,9 +147,6 @@ var radialAxisAttrs = {
     }
 };
 
-// radial title is not gui-editable, so it needs dflt: '', similar to carpet axes.
-radialAxisAttrs.title.text.dflt = '';
-
 extendFlat(
     radialAxisAttrs,
 

src/plots/ternary/layout_attributes.js

@@ -16,7 +16,10 @@ var overrideAll = require('../../plot_api/edit_types').overrideAll;
 var extendFlat = require('../../lib/extend').extendFlat;
 
 var ternaryAxesAttrs = {
-    title: axesAttrs.title,
+    title: {
+        text: axesAttrs.title.text,
+        font: axesAttrs.title.font
+    },
     color: axesAttrs.color,
     // ticks
     tickmode: axesAttrs.tickmode,