fix(highlight): optional startinline

Some languages require a startline (such as `<?php` for PHP).
This forces the snippets to have this startline to be (completly) highlighted.
By setting this option to `True`, the startline becomes optional.

bin/highlight.py

@@ -93,5 +93,5 @@ def _wrap_table(self, inner):
 
 def highlight(code, language):
     """ Pretty html export of ``code`` using syntax highlighting """
-    lexer = get_lexer_by_name(language)
+    lexer = get_lexer_by_name(language, startinline=True)
     return pygments.highlight(code, lexer, _html_formatter)