Complete ICU4N to production release

ICU4J is Lucene's biggest dependency. Several attempts have been made to utilize various alternatives:

1. ICU4NET
2. icu-dotnet

But we ran into several issues:

1. Lack of support for 32/64 bit
2. Lack of support for .NET Standard Platforms
3. Lack of features, and problems when trying to implement them
4. Lack of thread safety

We finally ended up doing a direct port of about 40% of ICU4J's features in order to support Lucene.NET. The project is named ICU4N, and is progressing in an external GitHub repository. There are several up-for-grabs issues that we could use some help with to get Lucene.NET into production.

https://github.com/NightOwl888/ICU4N