If anybody is interested:
I've translated utf8proc to FreePascal.
The original C code and documentation can be found here: http://www.flexiguided.de/publications.utf8proc.en.html It's an almost 1:1 translation, so the code looks a bit like C ;-) Please respect the licenses of the original code.
Feel free to fix bugs if you find any. I'm not a C programmer but the translation seems to work.
Have fun!
http://www.theo.ch/lazarus/utf8proc_pas.zip