Implement Sass (#568)

* Move all images to assets/img

* Move all scripts to assets/js

* Move all webfonts to assets/webfonts

* Move all files to assets/files

* Move css to assets/css and add imports

* Adjust all references to assets folder

* Fix tor icon path

* Rewrite custom css to sass and add variables

* Change ?v on style.css to 5.

* Enable Sass minification

* Remove CryptoPaper-full.7z

assets/img/flags/cw.svg

@@ -0,0 +1,14 @@
+<svg xmlns="http://www.w3.org/2000/svg" height="480" width="640" xmlns:xlink="http://www.w3.org/1999/xlink">
+  <defs>
+    <path id="b" d="M0-1l.225.69H.95L.364.12l.225.69L0 .383-.588.81l.225-.692L-.95-.31h.725z"/>
+    <clipPath id="a">
+      <path fill-opacity=".67" d="M0 0h682.67v512H0z"/>
+    </clipPath>
+  </defs>
+  <g clip-path="url(#a)" transform="scale(.94)">
+    <path fill="#002b7f" d="M0 0h768v512H0z"/>
+    <path fill="#f9e814" d="M0 320h768v64H0z"/>
+    <use xlink:href="#b" transform="scale(42.67)" height="9000" width="13500" y="2" x="2" fill="#fff"/>
+    <use xlink:href="#b" transform="scale(56.9)" height="9000" width="13500" y="3" x="3" fill="#fff"/>
+  </g>
+</svg>