Remove certain offensive words from jCaptcha

Hi! Could you please investigate if some offensive words could be removed from the jCaptcha library?

This was reported by an XWiki user, but I found that this is actually general issue that happens on other tools as well that use jCaptcha: https://stackoverflow.com/questions/2555966/is-there-a-way-to-filter-out-offensive-words-from-jcaptcha

Thank you!