Fixes #976 Emails records deletion during migration is addressed

Deletion of emails records during migration has been addressed.

See merge request !547

Zip file corruption.

As call time pass by reference is deprecated [Ref](https://www.php.net/manual/en/language.references.pass.php), we need to completely remove reference to this.

Package import and export is one of the place using dZip and dUnzip library, Which has call time pass by reference, has been cleaned up.

See merge request !546

Zip file corruption is addressed, By deperacting call by reference and filesize update for proper download

Fixed various Italian translations.

fix js requestReminder error when calendar module is not active!

Loading request reminder cause JS error when calendar module is not active.

See merge request !539

Fixes #1227 phpMailer updated for UTF-8 default encoding

See merge request !537

Fixes #1234 Attachments in Emails should have proper filename display

See merge request !536

#1227 sets phpmailer encoding to the encoding specified in config.inc.php when creating new instance of Vtiger_Mailer

See merge request !525

Fixes #1183 Reference fields title

See merge request !535

Fixes #1184 Field delete event handler is registered

See merge request !534

Fixes #1232 Displayed report is empty as picklist values failed to retrieve

See merge request !533

Fixes #1189 Calendar related module added to reference field

See merge request !532

Fixes #1233 Modtracker should update non-admin user

See merge request !531

fix #1229 Syntax error, wrong brace

See merge request !526