int tableWidth(String cellSeparator) {
        return columnWidths.values().stream()
                .reduce(0, (a, b) -> a + b)
                + cellSeparator.length() * (columnWidths.size() - 1);
    }
@author Nico Bergemann <barracuda415 at yahoo.de>
disunity-cli/src/main/java/info/ata4/disunity/cli/util/TextTableFormat.java