Make lineWithFocusChart have consistent x and y value getters

lineWithFocusChart uses two separate line charts, and this change
ensures that any x/y value getter (e.g. `chart.x(...)`) set on the main
line chart is also migrated to the focus chart.

nv.d3.js

@@ -3552,6 +3552,8 @@ nv.models.lineWithFocusChart = function() {
       lines2
         .width(availableWidth)
         .height(availableHeight2)
+        .x(lines.x())
+        .y(lines.y())
         .color(data.map(function(d,i) {
           return d.color || color[i % color.length];
         }).filter(function(d,i) { return !data[i].disabled }));

src/models/lineWithFocusChart.js

@@ -104,6 +104,8 @@ nv.models.lineWithFocusChart = function() {
       lines2
         .width(availableWidth)
         .height(availableHeight2)
+        .x(lines.x())
+        .y(lines.y())
         .color(data.map(function(d,i) {
           return d.color || color[i % color.length];
         }).filter(function(d,i) { return !data[i].disabled }));