Allow changing subkey expiry time.

Needs GPGME 1.15.0.
Using the same UI for changing expiry time of the primary secret key.

PopupExpiryTime.cpp

@@ -22,6 +22,7 @@ PopupExpiryTime::PopupExpiryTime(WWidget * anchorWidget, TransientMessageWidget
     m_tmwMessage = txtMessage;
     m_cwMain = NULL;
     m_keyFpr = WString::Empty;
+    m_subkeyFpr = WString::Empty;
     /*
      * Trade-off.
      * When the calendar of WDateEdit is clicked, this popup gets hidden,
@@ -82,6 +83,11 @@ const string PopupExpiryTime::GetExpiryTime() const
     return m_deExpiry->text().toUTF8();
 }
 
+const ulong PopupExpiryTime::GetExpiry() const
+{
+    return ((WDate::currentDate().daysTo(m_deExpiry->date())) * 24 * 3600);
+}
+
 void PopupExpiryTime::ShowPassphrase(bool show)
 {
     // See comments in PopupCertifyUserId::ShowPassphrase