Encode directly from string in one step only

Actually the **Encode** node receive only a `word array` as payload that is obtained easily decoding a `string` with **Decode** node.

But is a little bit tedious to decode a string just to encode it as Base64 for example.

This issue is to enhance the **Encode** and **Decode** node to do a combo of decode/encode in only one step without remove the ability to do just one of the actions.