implement images

test/hopdown.test.ts

@@ -24,6 +24,7 @@ suite('Markdown to HTML Round-Trips', () => {
         assert('inline code',    '`code`',          '<p><code>code</code></p>');
         assert('bold+italic',    '***bi***',        '<p><strong><em>bi</em></strong></p>');
         assert('link',           '[t](http://x)',   '<p><a href="http://x" title="">t</a></p>');
+        assert('image',          '![text](src.png "title")', '<p><img src="src.png" alt="text" title="title"></p>');
         assert('mixed',          'a **b** *c* `d`', '<p>a <strong>b</strong> <em>c</em> <code>d</code></p>');
         assert('code then bold', '`a` **b**',       '<p><code>a</code> <strong>b</strong></p>');
         assert('nested, ummatched italic',  '**i* b**',  '<p><strong>i* b</strong></p>');
@@ -293,4 +294,9 @@ suite('Markdown to Editor Nodes Round-Trips', () => {
         assertInline('link', '[label](url "title")', '<a href="url" title="title">label</a>');
     });
 
+    describe('image', () => {
+        assertInline('image', '![alt](url)', '<img src="url" alt="alt" title="">');
+        assertInline('image', '![alt](url "title")', '<img src="url" alt="alt" title="title">');
+    });
+
 });