files_reader: more PDF changes, working outline,progress report, starting experiment with preloading next page(s)

files_reader/vendor/pdfjs/css/main.css

@@ -210,6 +210,7 @@ body {
     display: flex;
     align-items: center;
     justify-content: center;
+    overflow: hidden;
 }
 
 #viewer canvas {
@@ -336,6 +337,59 @@ body {
     opacity: 0 !important;
 }
 
+/* progressbar (loading/unarchiving) */
+
+#progress {
+	position: fixed;
+	z-index: 10;
+	width: 100%;
+}
+
+.progress, .bar {
+    width: 100%;
+    height: 0.3em;
+    margin: 0;
+    padding: 0;
+    display: inline-block;
+}
+.progress {
+    border: none;
+}
+.bar {
+    width: 0;
+    background-color: red;
+    box-shadow: 0px 1px 3px rgba(0,0,0,.6);
+}
+
+.message {
+    margin: 3em;
+}
+
+.message-icons {
+    font-size: 3em;
+    color: lightgrey;
+    vertical-align: middle;
+}
+.message-text {
+    font-size: 1.5em;
+    color: black;
+}
+
+.active {
+    color:black;
+}
+
+.ok {
+    color:green;
+}
+
+.error {
+    color:red;
+}
+
+/* END progressbar */
+
+
 @media only screen and (max-width: 1040px) {
 /*
   #viewer{