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/sj.svg

@@ -0,0 +1,14 @@
+<svg xmlns="http://www.w3.org/2000/svg" height="480" width="640" version="1">
+  <defs>
+    <clipPath id="a">
+      <path fill-opacity=".67" d="M-24.803 48.27h570.47v427.85h-570.47z"/>
+    </clipPath>
+  </defs>
+  <g clip-path="url(#a)" transform="translate(27.826 -54.153) scale(1.1219)">
+    <path fill="#fff" d="M0 0h512v512H0z"/>
+    <path fill-rule="evenodd" fill="#fff" d="M-80 .158h699.74v511.84H-80z"/>
+    <path fill-rule="evenodd" fill="#d72828" d="M-99.213-23.039h212.94v221.47h-212.94zM237.42-23.039h407.46v221.47H237.42zM-99.213 321.67h210v225.76h-210zM240 323.79h404.88v223.65H240z"/>
+    <path fill-rule="evenodd" fill="#003897" d="M144.65-23.039h64.425v570.47H144.65z"/>
+    <path fill-rule="evenodd" fill="#003897" d="M-124.02 224.84h768.9v63.444h-768.9z"/>
+  </g>
+</svg>