add topic sorting & js to support it

data/static/icons/dragger.svg

@@ -0,0 +1,46 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!-- Created with Inkscape (http://www.inkscape.org/) -->
+
+<svg
+   width="24"
+   height="24"
+   viewBox="0 0 24 24"
+   version="1.1"
+   id="svg1"
+   xmlns="http://www.w3.org/2000/svg"
+   xmlns:svg="http://www.w3.org/2000/svg">
+  <defs
+     id="defs1" />
+  <g
+     id="layer1">
+    <rect
+       style="fill:#000000;stroke:none;stroke-width:0.999996;stroke-linecap:round;stroke-linejoin:round"
+       id="rect1"
+       width="16"
+       height="2"
+       x="4"
+       y="8" />
+    <rect
+       style="fill:#000000;stroke:none;stroke-width:0.999996;stroke-linecap:round;stroke-linejoin:round"
+       id="rect2"
+       width="16"
+       height="2"
+       x="4"
+       y="11" />
+    <rect
+       style="fill:#000000;stroke:none;stroke-width:0.999996;stroke-linecap:round;stroke-linejoin:round"
+       id="rect3"
+       width="16"
+       height="2"
+       x="4"
+       y="14" />
+    <path
+       style="fill:#000000;stroke:none;stroke-linecap:round;stroke-linejoin:round"
+       d="m 6,6 6,-6 6,6 H 16 L 12,2 8,6 Z"
+       id="path3" />
+    <path
+       style="fill:#000000;stroke:none;stroke-linecap:round;stroke-linejoin:round"
+       d="m 6,18 6,6 6,-6 h -2 l -4,4 -4,-4 z"
+       id="path4" />
+  </g>
+</svg>