Add mermaid support

browser/components/render/MermaidRender.js

@@ -0,0 +1,28 @@
+import mermaidAPI from 'mermaid'
+
+function getRandomInt (min, max) {
+  return Math.floor(Math.random() * (max - min)) + min
+}
+
+function getId () {
+  var pool = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'
+  var id = 'm-'
+  for (var i = 0; i < 7; i++) {
+    id += pool[getRandomInt(0, 16)]
+  }
+  return id
+}
+
+function render (element, content) {
+  try {
+    mermaidAPI.render(getId(), content, (svgGraph) => {
+      element.innerHTML = svgGraph
+    })
+  } catch (e) {
+    console.error(e)
+    element.className = 'mermaid-error'
+    element.innerHTML = 'mermaid diagram parse error: ' + e.message
+  }
+}
+
+export default render