Use local copy of C3 with some accessibility support added

Based on c3js/c3#2317

c3.css

@@ -0,0 +1,180 @@
+/*-- Chart --*/
+.c3 svg {
+  font: 10px sans-serif;
+  -webkit-tap-highlight-color: transparent; }
+
+.c3 path, .c3 line {
+  fill: none;
+  stroke: #000; }
+
+.c3 text {
+  -webkit-user-select: none;
+  -moz-user-select: none;
+  user-select: none; }
+
+.c3-legend-item-tile,
+.c3-xgrid-focus,
+.c3-ygrid,
+.c3-event-rect,
+.c3-bars path {
+  shape-rendering: crispEdges; }
+
+.c3-chart-arc path {
+  stroke: #fff; }
+
+.c3-chart-arc rect {
+  stroke: white;
+  stroke-width: 1; }
+
+.c3-chart-arc text {
+  fill: #fff;
+  font-size: 13px; }
+
+/*-- Axis --*/
+/*-- Grid --*/
+.c3-grid line {
+  stroke: #aaa; }
+
+.c3-grid text {
+  fill: #aaa; }
+
+.c3-xgrid, .c3-ygrid {
+  stroke-dasharray: 3 3; }
+
+/*-- Text on Chart --*/
+.c3-text.c3-empty {
+  fill: #808080;
+  font-size: 2em; }
+
+/*-- Line --*/
+.c3-line {
+  stroke-width: 1px; }
+
+/*-- Point --*/
+.c3-circle._expanded_ {
+  stroke-width: 1px;
+  stroke: white; }
+
+.c3-selected-circle {
+  fill: white;
+  stroke-width: 2px; }
+
+/*-- Bar --*/
+.c3-bar {
+  stroke-width: 0; }
+
+.c3-bar._expanded_ {
+  fill-opacity: 1;
+  fill-opacity: 0.75; }
+
+/*-- Focus --*/
+.c3-target.c3-focused {
+  opacity: 1; }
+
+.c3-target.c3-focused path.c3-line, .c3-target.c3-focused path.c3-step {
+  stroke-width: 2px; }
+
+.c3-target.c3-defocused {
+  opacity: 0.3 !important; }
+
+/*-- Region --*/
+.c3-region {
+  fill: steelblue;
+  fill-opacity: .1; }
+
+/*-- Brush --*/
+.c3-brush .extent {
+  fill-opacity: .1; }
+
+/*-- Select - Drag --*/
+/*-- Legend --*/
+.c3-legend-item {
+  font-size: 12px; }
+
+.c3-legend-item-hidden {
+  opacity: 0.15; }
+
+.c3-legend-background {
+  opacity: 0.75;
+  fill: white;
+  stroke: lightgray;
+  stroke-width: 1; }
+
+/*-- Title --*/
+.c3-title {
+  font: 14px sans-serif; }
+
+/*-- Tooltip --*/
+.c3-tooltip-container {
+  z-index: 10; }
+
+.c3-tooltip {
+  border-collapse: collapse;
+  border-spacing: 0;
+  background-color: #fff;
+  empty-cells: show;
+  -webkit-box-shadow: 7px 7px 12px -9px #777777;
+  -moz-box-shadow: 7px 7px 12px -9px #777777;
+  box-shadow: 7px 7px 12px -9px #777777;
+  opacity: 0.9; }
+
+.c3-tooltip tr {
+  border: 1px solid #CCC; }
+
+.c3-tooltip th {
+  background-color: #aaa;
+  font-size: 14px;
+  padding: 2px 5px;
+  text-align: left;
+  color: #FFF; }
+
+.c3-tooltip td, .c3-tooltip th[scope='row'] {
+  font-size: 13px;
+  padding: 3px 6px;
+  background-color: #fff;
+  border-left: 1px dotted #999;
+  color: black;
+  font-weight: normal; }
+
+.c3-tooltip td > span, .c3-tooltip th[scope='row'] > span {
+  display: inline-block;
+  width: 10px;
+  height: 10px;
+  margin-right: 6px; }
+
+.c3-tooltip td.value {
+  text-align: right; }
+
+/*-- Area --*/
+.c3-area {
+  stroke-width: 0;
+  opacity: 0.2; }
+
+/*-- Arc --*/
+.c3-chart-arcs-title {
+  dominant-baseline: middle;
+  font-size: 1.3em; }
+
+.c3-chart-arcs .c3-chart-arcs-background {
+  fill: #e0e0e0;
+  stroke: #FFF; }
+
+.c3-chart-arcs .c3-chart-arcs-gauge-unit {
+  fill: #000;
+  font-size: 16px; }
+
+.c3-chart-arcs .c3-chart-arcs-gauge-max {
+  fill: #777; }
+
+.c3-chart-arcs .c3-chart-arcs-gauge-min {
+  fill: #777; }
+
+.c3-chart-arc .c3-gauge-value {
+  fill: #000;
+  /*  font-size: 28px !important;*/ }
+
+.c3-chart-arc.c3-target g path {
+  opacity: 1; }
+
+.c3-chart-arc.c3-target.c3-focused g path {
+  opacity: 1; }