[FEATURE] Add subjectField to Form Wizard TS

Change-Id: Ic3d28b9f641e1d20eb2fa99b0100def419cb17f1
Resolves: #32132
Releases: 4.7
Reviewed-on: http://review.typo3.org/8888
Reviewed-by: Markus Klein
Reviewed-by: Philipp Gampe
Reviewed-by: Stefan Neufeind
Tested-by: Philipp Gampe
Reviewed-by: Steffen Ritter
Tested-by: Steffen Ritter

typo3/sysext/form/Classes/System/Postprocessor/Mail.php

@@ -104,6 +104,8 @@ class tx_form_System_Postprocessor_Mail {
 	protected function setSubject() {
 		if (isset($this->typoScript['subject'])) {
 			$subject = $this->typoScript['subject'];
+		} elseif ($this->requestHandler->has($this->typoScript['subjectField'])) {
+			$subject = $this->requestHandler->get($this->typoScript['subjectField']);
 		} else {
 			$subject = 'Formmail on ' . t3lib_div::getIndpEnv('HTTP_HOST');
 		}
@@ -350,4 +352,4 @@ class tx_form_System_Postprocessor_Mail {
 		}
 	}
 }
-?>
\ No newline at end of file
+?>