Fix some tests failures

Currently, I see some tests failures (at least with Python 3):

```
ERROR: testHighlightLinesWithColon (tests.test_extensions.TestCodeHilite)
ERROR: Test Fenced Code with Highlighted Lines.
MarkdownSyntaxError: TestSyntax: "extensions/extra/tables_and_attr_list"
```

The first two happen because Pygments' `get_list_opt` requires a list, but gets a generator instead. The last one happens because the HTML file has a trailing newline, while it shouldn't.