Description:
------------
The highlight_string function fails to properly indent lines that begin with a single space.

I suspect highlight_file has the same problem, but have not tested it.

In the reproduce code (below), the line ' *' actually renders as:

<br /> *<br />

Instead of the expected:

<br />&nbsp;*<br />

So, I guess if a line begins with a single space, that space needs to be converted into '&nbsp;' even though it is a singleton.

Reproduce code:
---------------
<?php

$comment = array ('/*', '*', ' *', '  *', "\t*/");
$comment = join ("\n", $comment);
highlight_string ($comment);

?>


Expected result:
----------------
<code><span style="color: #000000">
/*<br />*<br />&nbsp;*<br />&nbsp;&nbsp;*<br />&nbsp;&nbsp;&nbsp;&nbsp;*/</span>
</code>


Actual result:
--------------
<code><span style="color: #000000">
/*<br />*<br /> *<br />&nbsp;&nbsp;*<br />&nbsp;&nbsp;&nbsp;&nbsp;*/</span>
</code>