Patch: specify alternate image in html_alt without php code

Several people have asked how to display an image when Flash is not available. The best answer to this is in the FAQ for this module: http://drupal.org/node/318728. Unfortunately, this solution involves php code and is not available when using the embedding syntax in the form [swf file="myFile.swf"]

With the embedding syntax, only plain text can be specified: [swf file="myFile.swf" othervars="html_alt=My alternate plain text"]. It would be good to have some way of passing html code to the swf() function, but in many cases all that is needed is probably just an image. So I have provided a small patch that allows exactly that. The syntax for this is:
[swf file="myFile.swf" othervars="html_alt=image:/images/myImage.png,alt:My alternate image text."]

This will create an alternate html of the form
<p><img src="/images/myImage.png" alt="My alternate image text." /></p>

To use this, you need to use a javascript embedding method such as swfobject or jquery.flash.

Warning: This patch needs to be reviewed for security and is only intended to be accessed by trusted editors of a site. If you allow your users access to the swftools flash filter, don't use this patch without reviewing it for security, as turns user supplied content into html.