New functionality: Unicode -> Hex, UTF-8 -> Hex

what about add this new functionality to plugin?
```
     Unicode -> Hex
     Hex -> Unicode
     UTF-8 -> Hex
     Hex -> UTF-8
```

or probably best solution is look at the document setting (ANSI, UTF-8, Unicode...) and do it automatically, just change caption in menu universally: 
```
     Text -> Hex
     Hex -> Text
```
keep text conversion on user if he need different format