added b64 encode/decode to MString.

testing/compile

@@ -1,4 +1,4 @@
 #!/bin/bash
 g++ -g -std=c++20 -o zstring_test zstring_test.cpp -I.. -L.. -lCoreUtils
-g++ -g -std=c++20 -o mstring_test mstring_test.cpp -I.. -L.. -lCoreUtils
+g++ -g -std=c++20 -o mstring_test mstring_test.cpp -I.. -L.. -lCoreUtils -lb64
 g++ -o jstring_test jstring_test.cpp -I.. -L.. -lCoreUtils

testing/mstring_test.cpp

@@ -95,8 +95,19 @@ int main(int argc, char **argv) {
    test28 = test29;
    std::cout << "int: " << test28 << std::endl;
 
-   coreutils::MString test30 = "ABCDEF";
+   coreutils::MString test30 = "ABCDEF0123";
    std::cout << test30 << " to hex " << test30.toHex() << " from hex " << test30.toHex().fromHex() << std::endl;
+
+   std::cout << test30 << " to lower " << test30.toLower() << std::endl;
+
+   coreutils::MString test31 = "abcdef0123";
+   std::cout << test31 << " to upper " << test31.toUpper() << std::endl;
+
+   coreutils::MString test32 = "This is a test of converting this string to base64";
+   std::cout << test32 << " to base64 " << test32.toBase64() << std::endl;
+
+   coreutils::MString test33 = test32.toBase64();
+   std::cout << test33 << " from base64 " << test33.fromBase64() << std::endl;   
    
    return 0;
 }