wrap double u_getNumericValue(UChar32 c)

Question: *This is a per-character function; How to vectorise it?*

From the manual: https://unicode-org.github.io/icu-docs/apidoc/released/icu4c/uchar_8h.html

Get the numeric value for a Unicode code point as defined in the Unicode Character Database.

A "double" return type is necessary because some numeric values are fractions, negative, or too large for int32_t.

For characters without any numeric values in the Unicode Character Database, this function will return U_NO_NUMERIC_VALUE. Note: This is different from the Unicode Standard which specifies NaN as the default value. (NaN is not available on all platforms.)

Similar to java.lang.Character.getNumericValue(), but u_getNumericValue() also supports negative values, large values, and fractions, while Java's getNumericValue() returns values 10..35 for ASCII letters.