Linkification testing

[macchiati]

Some preliminary code to check the linkification algorithm and generate test cases.

[macchiati]

TODO:

1. Update data file & test data generator to match rev 1 draft 5.
2. Add newer test data from ICANN.
3. Change the data file folder to /Public//linkification/
4. Change the filename SerializationTest.txt to FormattingTest.txt
5. Create a unicodetools PR with the code, get it reviewed & merged.