mbyte character support

[suliveevil]

Would you please add mbyte character support?

Underline all the same single character in range [\u4e00-\u9fa5] is all I need.

Thank you very much.

[itchyny]

This plugin already supports some multi-byte alphabets. But I cannot accept adding such a wider range characters because it doesn't work with set regexpengine=1. I don't think adding Chinese characters is useful because the entire line will be underlined.

[suliveevil]

You are right, underline a character is meaningless, I should find a way to achieve it when using *.