Initial implementation of clipboard support

With tooltips

theme/book.css

@@ -859,3 +859,21 @@ a:hover > .hljs {
 .light a > .hljs {
   color: #4183c4;
 }
+
+.tooltiptext {
+  visibility: hidden;
+  background-color: black;
+  color: #fff;
+  opacity: 0.8;
+  text-align: center;
+  border-radius: 6px;
+  padding: 5px 8px;
+  margin: 5px;
+  left: -250%;
+  bottom: 100%;
+  position: absolute;
+  z-index: 1000;
+}
+.tooltipped .tooltiptext {
+  visibility: visible;
+}

theme/book.js

@@ -191,15 +191,35 @@ $( document ).ready(function() {
             buttons = pre_block.find(".buttons");
         }
         buttons.prepend("<i class=\"fa fa-play play-button\"></i>");
+        buttons.prepend("<i class=\"fa fa-copy clip-button\"><i class=\"tooltiptext\"></i></i>");
 
         buttons.find(".play-button").click(function(e){
             run_rust_code(pre_block);
         });
+        buttons.find(".clip-button").mouseout(function(e){
+            e.currentTarget.setAttribute('class', 'fa fa-copy clip-button');
+        });
     });
 
+    var clipboardSnippets = new Clipboard('.clip-button', {
+        text: function(trigger) {
+           return trigger.parentElement.parentElement.textContent;
+        }
+    });
+    clipboardSnippets.on('success', function(e) {
+            e.clearSelection();
+            showTooltip(e, "Copied!");
+    });
+    clipboardSnippets.on('error', function(e) {
+            showTooltip(e, "Clipboard error!");
+    });
 
 });
 
+function showTooltip(elem, msg) {
+    elem.trigger.firstChild.innerText=msg;
+    elem.trigger.setAttribute('class', 'fa fa-copy tooltipped');
+}
 
 function run_rust_code(code_block) {
     var result_block = code_block.find(".result");

theme/index.hbs

@@ -24,6 +24,8 @@
         <!-- MathJax -->
         <script type="text/javascript" src="https://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML"></script>
 
+        <!-- Clipboard.js -->
+        <script src="https://cdn.jsdelivr.net/clipboard.js/1.6.1/clipboard.min.js"></script>
         <!-- Fetch JQuery from CDN but have a local fallback -->
         <script src="https://code.jquery.com/jquery-2.1.4.min.js"></script>
         <script>