Allow open on all HTML parts

Currently, it is not possible to open a mail with HTML as main body part.
This fixes it by checking if the content type is of `HTML` and allow it
to be opened. This resolves issue #89.

Signed-off-by: pschwabauer <pschwabauer@intevation.de>
(cherry picked from commit 9ab93f257b)

kmail/kmmimeparttree.cpp

@@ -131,7 +131,8 @@ void KMMimePartTree::itemRightClicked( TQListViewItem* item,
     else {
         TQPopupMenu* popup = new TQPopupMenu;
         if ( mCurrentContextMenuItem->node()->nodeId() > 2 &&
-             mCurrentContextMenuItem->node()->typeString() != "Multipart" ) {
+             mCurrentContextMenuItem->node()->typeString() != "Multipart" ||
+             mCurrentContextMenuItem->node()->subTypeString() == "HTML" ) {
           popup->insertItem( SmallIcon("document-open"), i18n("to open", "Open"), this, TQ_SLOT(slotOpen()) );
           popup->insertItem( i18n("Open With..."), this, TQ_SLOT(slotOpenWith()) );
           popup->insertItem( i18n("to view something", "View"), this, TQ_SLOT(slotView()) );