Creates a valid path to the unit in the namespace.
function mkdir(units, name) {
        if (name !== "") {
            var parts = name.split(".");
            var path = "";
            for (var i = 0, len = parts.length; i < len; i++) {
                var part = parts[i];
                path += part;
                if (units[part] == null) {
                    units[part] = {};
                } else if (typeof units[part] !== "object") {
                    error("Cann't init unit '" + name
                            + "' because path element '" + path
                            + "' isn't an object");
                }
                units = units[part];
                path += ".";
            }
        }
        return units;
    }