Move everything related to synopsis into subfolder

Clean up some unused and generated files

doc/synopsis/synopsis.css

@@ -0,0 +1,13 @@
+#quicklinks {
+  line-height: 130%;
+}
+
+#quicklinks.sidebar {
+  overflow-y: scroll;
+  height: 100%;
+  position: fixed;
+}
+
+#quicklinks a {
+  display: block;
+}