Clever. Looks like it's using all of the diacritic marks to encode information onto a / character. (it's easy to see if you use a large enough font)
This would suggest this means that you can create a dynamic font/character in unicode. I had no idea this was possible, can someone confirm/slap me down for saying silly things?
An important task of unicode encoding/decoding is inter-converting between the two forms. For example if you require a name to be unique, and one form uses combining characters and the other doesn't, they are identical, but different.
It's not actually compression, according to the author, the 'single character' is 6x larger than the original UTF8 bytes.