ICU allows isolated surrogates in strings

Just as a further indication that we are making the right choice about 
allowing surrogates internally, this is extracted from an email from the 
co-founder and president of Unicode, "ICU treats unpaired surrogates as 
if they were unassigned characters, when manipulating them as strings. 
That is a common technique, see discussions of  "UnicodeString" in 
Chapter 3."

• ICU allows isolated surrogates in strings by karl williamson