Fix invalid unicode string length

[coveralls]

Pull Request Test Coverage Report for Build 23

• 3 of 3 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.01%) to 87.606%

---

Totals
Change from base Build 19:	0.01%
Covered Lines:	668
Relevant Lines:	723

---

💛 - Coveralls

[ChiefOfGxBxL]

Hi @dulingzhi, thanks for catching this mistake! As a minor update, would you please update the HexBuffer string test (https://github.com/ChiefOfGxBxL/WC3MapTranslator/blob/master/test/HexBufferTest.js#L15) to demonstrate the unicode functionality? Once that's there I'll be happy to approve this! 😃

[dulingzhi]

Hi @ChiefOfGxBxL I added addString with test cases from other human languages.