Added lineIsWhitespace function.

testing/zstring_test.cpp

@@ -63,5 +63,12 @@ int main(int argc, char **argv) {
    coreutils::ZString test5 = "this is a test of the Exclude tokenization without\n a line end.";
    coreutils::ZString test6 = test5.getTokenExclude("\n");
    std::cout << test6 << std::endl;
+
+   coreutils::ZString test7 = "this is a line\n       \nthis is another line\n     ";
+   std::cout << test7.lineIsWhitespace() << test7.goeol() << std::endl;
+   std::cout << test7.lineIsWhitespace() << test7.goeol() << std::endl;
+   std::cout << test7.lineIsWhitespace() << test7.goeol() << std::endl;
+   std::cout << test7.lineIsWhitespace() << test7.goeol() << std::endl;
+   
    
 }