UnicodeTrieBuilder and accompanying classes ported from the following sources:

https://github.com/dotnet/runtime MIT
https://github.com/unicode-org/icu ICU License (Permissive)
https://github.com/toptensoftware/RichTextKit Apache 2.0
https://github.com/foliojs/unicode-trie MIT

Further information and implementation examples can be found at 
http://www.unicode.org/reports/tr41/tr41-26.html