Add comment edit icon and form

Show an icon next to the comment deletion icon, which leads to a
comment edit form.

Signed-off-by: Marcel Korpel <marcel.korpel@gmail.com>
Signed-off-by: Lukas Fleischer <lfleischer@archlinux.org>

web/html/images/pencil.min.svg

@@ -0,0 +1,3 @@
+<svg xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns="http://www.w3.org/2000/svg" height="8" width="8" version="1.1" xmlns:cc="http://creativecommons.org/ns#" xmlns:dc="http://purl.org/dc/elements/1.1/" viewBox="0 0 8 8">
+<path fill="#36a" d="m6 0l-1 1 2 2 1-1-2-2zm-2 2l-4 4v2h2l4-4-2-2z"/>
+</svg>

web/html/images/pencil.svg

@@ -0,0 +1,55 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<svg
+   xmlns:dc="http://purl.org/dc/elements/1.1/"
+   xmlns:cc="http://creativecommons.org/ns#"
+   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+   xmlns:svg="http://www.w3.org/2000/svg"
+   xmlns="http://www.w3.org/2000/svg"
+   xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
+   xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
+   width="8"
+   height="8"
+   viewBox="0 0 8 8"
+   id="svg2"
+   version="1.1"
+   inkscape:version="0.91 r13725"
+   sodipodi:docname="pencil-arch.svg">
+  <metadata
+     id="metadata10">
+    <rdf:RDF>
+      <cc:Work
+         rdf:about="">
+        <dc:format>image/svg+xml</dc:format>
+        <dc:type
+           rdf:resource="http://purl.org/dc/dcmitype/StillImage" />
+        <dc:title></dc:title>
+      </cc:Work>
+    </rdf:RDF>
+  </metadata>
+  <defs
+     id="defs8" />
+  <sodipodi:namedview
+     pagecolor="#ffffff"
+     bordercolor="#666666"
+     borderopacity="1"
+     objecttolerance="10"
+     gridtolerance="10"
+     guidetolerance="10"
+     inkscape:pageopacity="0"
+     inkscape:pageshadow="2"
+     inkscape:window-width="659"
+     inkscape:window-height="480"
+     id="namedview6"
+     showgrid="false"
+     inkscape:zoom="29.5"
+     inkscape:cx="4"
+     inkscape:cy="4"
+     inkscape:window-x="0"
+     inkscape:window-y="0"
+     inkscape:window-maximized="0"
+     inkscape:current-layer="svg2" />
+  <path
+     d="M6 0l-1 1 2 2 1-1-2-2zm-2 2l-4 4v2h2l4-4-2-2z"
+     id="path4"
+     style="fill:#3366aa;fill-opacity:1" />
+</svg>