Serious work on JString and some minor MString ajustments.

testing/mstring_test.cpp

@@ -8,8 +8,11 @@ int main(int argc, char **argv) {
    std::cout << "char * operator=: [" << test1 << "]." << std::endl;
    test1 = "new value.";
    std::cout << "char * operator=: [" << test1 << "]." << std::endl;
+   std::cout << "001" << std::endl;
    std::string test11 = "this is a test";
+   std::cout << "002" << std::endl;
    coreutils::MString test12 = test11;
+   std::cout << "003" << std::endl;
    std::cout << "assign from std::string: [" << test12 << "]." << std::endl;   
 
    coreutils::MString test2("this is another test.");