Whitespace after toRichTextObject() + fix

[xairoo]

Using toRichTextObject() to encode a HTML string:

<strong>bold</strong>, <em>italic</em>, <strong><em>bold+italic</em></strong>

becomes:
bold , italic , _bold+italic_

I fixed this for me:
@PHPExcel/Classes/PHPExcel/Helper/HTML.php

    protected function parseElementNode(DOMElement $element) {
        $callbackTag = strtolower($element->nodeName);
        $this->stack[] = $callbackTag;

        $this->handleCallback($element, $callbackTag, $this->startTagCallbacks);

        $this->parseElements($element);
        $this->stringData .= ' ';
        array_pop($this->stack);

        $this->handleCallback($element, $callbackTag, $this->endTagCallbacks);
    }

Should be:

        $this->stringData .= ''; // whitespace removed

[MarkBaker]

This space is necessary in some cases, simply removing it may merge words together.... e.g. in the 42richText.php example, it removes the space between h2so4 and is and between 2<sup>3</sup> andequals`.