Unicode support

[super-betonamu-jin]

Even though it pulls in the ICU library as a dependency, it doesn’t seem as prepared for Unicode as I expected. For example, attempting to reverse a complex emoji, such as flags, can even crash the program. This makes me think the runtime is more fragile than I had previously believed.

[fredkiefer]

Could you please add a short example for this issue? This would help to understand and fix the problem.