Enclose exported Number in double quotes to ease Excel import

exported csv from phonebook will get the leading zero truncated with excel and calc.

So the number should also be enclosed in double Quotes like the "name".

Phonebook.class.php:

case "export":
header('Content-Type: text/csv');
header('Content-disposition: attachment; filename=phonebook.csv');
$numbers = \phonebook_list();
foreach ($numbers as $number => $values){
printf("\"%s\";\"%s\";\"%s\"\n", $values['name'], trim($number), $values['speeddial']);
}

before change the line read:

printf("\"%s\";%s;%s\n", $values['name'], trim($number), $values['speeddial']);

This modification makes Excel recognise the number as text and leaves it "as-is"