SendmailMailer: Impossible to set commandArgs

[KacerCZ]

Version: 4.0.0

Bug Description

Commit 0e236e4 breaks sending mails with set "From" when SendmailMailer::$commandArgs is also set.
In that case function mail() is invoked with 6 parameters instead of expected 5 parameters.

Steps To Reproduce

$mail = new \Nette\Mail\Message();
$mail->setFrom('test@example.com');

$mailer = new \Nette\Mail\SendmailMailer();
$mailer->commandArgs = '-finfo@example.com';
$mailer->send($mail);

Produces ArgumentCountError "mail() expects at most 5 arguments, 6 given".

Expected Behavior

Function mail() is successfully invoked.

Possible Solution

Command arguments from mailer must be concatenated with value from message.

[KacerCZ]

May be worth considering how command line argument can be handled when it is already present in commandArgs as presented in #78.