Set the MailService Charset before setting the body

msgHTML builds the text/plain part by converting the passed html to text in the current CharSet; the default Charset being iso-8859-1, most non-ascii characters are lost.

fixes #416

app/classes/Framadate/Services/MailService.php

@@ -68,10 +68,10 @@ class MailService {
             // Bodies
             $body = $body . ' <br/><br/>' . __('Mail', 'Thank you for your trust.') . ' <br/>' . NOMAPPLICATION . ' <hr/>' . __('Mail', "\"The road is long, but the way is clear…\"<br/>Framasoft lives only by your donations.<br/>Thank you in advance for your support https://soutenir.framasoft.org");
             $mail->isHTML(true);
+            $mail->CharSet = 'utf-8';
             $mail->msgHTML($body, ROOT_DIR, true);
 
             // Build headers
-            $mail->CharSet = 'UTF-8';
             $mail->addCustomHeader('Auto-Submitted', 'auto-generated');
             $mail->addCustomHeader('Return-Path', '<>');