Port of C's wcwidth() and wcswidth()
Determine columns needed for a fixed-size wide-character string
'한'length // => 1; // => 2'한글'length // => 2; // => 4
wcwidth() and its string version,
wcswidth() are defined by IEEE Std
1002.1-2001, a.k.a. POSIX.1-2001, and return the number of columns used
to represent the given wide character and string.