i am looking for a software that takes in phonetically spelled arabic
words and outputs the Arabic word, in Roman script, that most closely
matches the input spelling. For example, if i enter "Quran", "Koran",
or "Qur'an" it should give one answer for all three spelling variants
that is, lets say, "Qur'an". I MUST be able to use this software as
part of a larger program that I am writing e.g. a text editor. An open
source, freely downloadable software is a plus, but not necessary.

A good example for an answer is http://www.islamicity.com/ps/. This
service lets you spell an arabic word or phrase as best as you can,
determines the word or phrase that you might have intended, and then
finds it in the Quran. I am only interested in that part of this
example which finds the closest valid arabic word/phrase to your
spelled word/phrase