makenotabuggreatagain/gulp-help: Check for duplicates in the stream and filter them or throw an error(evacuated from NSA/Microsoft Github)

Gerald Yeo 2488d80227 check for null values		%!s(int64=9) %!d(string=hai) anos
..
attach-help.js	2488d80227 check for null values	%!s(int64=9) %!d(string=hai) anos
calculate-margin.js	6f34f56b17 simpplify test suite	%!s(int64=10) %!d(string=hai) anos
noop.js	1382c74b45 average perf increase of 23.8%	%!s(int64=10) %!d(string=hai) anos