Remove duplicate agreement in member_config #1788

- $config->agreements와 중복되는 $config->agreement는 삭제
- 회원가입폼(dispMemberSignUpForm)에 한하여, 첫 번째 약관의 내용을
  $member_config->agreement에 넣어주어 오래된 스킨과의 호환성을 유지함

modules/member/member.view.php

@@ -246,6 +246,9 @@ class memberView extends member
 		
 		$this->addExtraFormValidatorMessage();
 		
+		// Set a copy of the agreement for compatibility with old skins
+		$member_config->agreement = $member_config->agreements[1]->content ?? '';
+		
 		// Set a template file
 		$this->setTemplateFile('signup_form');
 	}