Rudder

Now that global variables declarations are properly handled (with a deep map of types) it can be useful to have several subvariables added to a given namespace.
Example:
```
declare sys.hostname.coucou.qwpeodfu.aswefo
declare sys.hostname.coucou.qwpeodfu.itsworking
declare sys.newvar
```

Note that adding this line will output an error since the hostname namespace already exists:
`declare sys.hostname`