Use time zone string instead of offset.

This is done by setting the TZ variable prior to calling localtime() or ctime().

There are a few calls to ctime()/localtime() which doesn’t adjust for time zone offset. This patch affects the behavior of these since the TZ variable is global.

modules/simple_away.cpp

@@ -189,7 +189,7 @@ private:
 			sReason = SIMPLE_AWAY_DEFAULT_REASON;
 
 		time_t iTime = time(NULL);
-		iTime += (time_t)(m_pUser->GetTimezoneOffset() * 60 * 60); // offset is in hours
+		setenv("TZ", m_pUser->GetTimezone().c_str(), 1);
 		CString sTime = ctime(&iTime);
 		sTime.Trim();
 		sReason.Replace("%s", sTime);