Added a [code] block to the problem markdown parser

Adds a code block to the problem markdown parser that translates
[code]
TestTest
[/code]
to
<pre><code>
TestTest
</code></pre>

AUTHORS

@@ -92,3 +92,4 @@ Felipe Montoya <felipe.montoya@edunext.co>
 Julia Hansbrough <julia@edx.org>
 Pavel Yushchenko <pavelyushchenko@gmail.com>
 Nicolas Chevalier <nicolas.chevalier@epitech.eu>
+Iain Dunning <idunning@mit.edu>

common/lib/xmodule/xmodule/js/spec/problem/edit_spec.coffee

@@ -314,6 +314,10 @@ describe 'MarkdownEditingDescriptor', ->
         
         bad tests require drivel
         </div>
+        
+        [code]
+        Code should be nicely monospaced.
+        [/code]
         """)
       expect(data).toEqual("""<problem>
         <p>Not a header</p>
@@ -382,5 +386,9 @@ describe 'MarkdownEditingDescriptor', ->
         
         <p>bad tests require drivel</p>
         </div>
+        
+        <pre><code>
+        Code should be nicely monospaced.
+        </code></pre>
         </problem>""")
     # failure tests

common/lib/xmodule/xmodule/js/src/problem/edit.coffee

@@ -268,18 +268,24 @@ class @MarkdownEditingDescriptor extends XModule.Descriptor
           var selectString = '<solution>\n<div class="detailed-solution">\nExplanation\n\n' + p1 + '\n</div>\n</solution>';
           return selectString;
       });
+      
+      // replace code blocks
+      xml = xml.replace(/\[code\]\n?([^\]]*)\[\/?code\]/gmi, function(match, p1) {
+          var selectString = '<pre><code>\n' + p1 + '</code></pre>';
+          return selectString;
+      });
 
-      // split scripts and wrap paragraphs
-      var splits = xml.split(/(\<\/?script.*?\>)/g);
+      // split scripts and preformatted sections, and wrap paragraphs
+      var splits = xml.split(/(\<\/?(?:script|pre).*?\>)/g);
       var scriptFlag = false;
       for(var i = 0; i < splits.length; i++) {
-        if(/\<script/.test(splits[i])) {
+        if(/\<(script|pre)/.test(splits[i])) {
           scriptFlag = true;
         }
         if(!scriptFlag) {
           splits[i] = splits[i].replace(/(^(?!\s*\<|$).*$)/gm, '<p>$1</p>');
         }
-        if(/\<\/script/.test(splits[i])) {
+        if(/\<\/(script|pre)/.test(splits[i])) {
           scriptFlag = false;
         }
       }