RFR: JDK-8200377 String::strip, String::stripLeading, String::stripTrailing

[Jim Laskey]

This feature introduces three String instance methods for removal of white space from the beginning and end of a string. Unlike String::trim, these methods use the Unicode definition of white space. Specifically, these methods use Character.isWhitespace(int codePoint) to detect space characters.

webrev: http://cr.openjdk.java.net/~jlaskey/8200377/webrev/index.html
jbs: https://bugs.openjdk.java.net/browse/JDK-8200377
csr: https://bugs.openjdk.java.net/browse/JDK-8200378