Move wxTipWindow members used only by wxTipWindowView there

No real changes, just move m_textLines and m_heightLine from wxTipWindow
to wxTipWindowView as they were only used by the latter and so can just
as well be its members.

Also use this as an opportunity to replace wxArrayString with wxVector.

include/wx/tipwin.h

@@ -16,8 +16,6 @@
 
 #include "wx/popupwin.h"
 
-#include "wx/arrstr.h"
-
 class WXDLLIMPEXP_FWD_CORE wxTipWindowView;
 
 // ----------------------------------------------------------------------------
@@ -65,9 +63,6 @@ protected:
     virtual void OnDismiss() wxOVERRIDE;
 
 private:
-    wxArrayString m_textLines;
-    wxCoord m_heightLine;
-
     wxTipWindowView *m_view;
 
     wxTipWindow** m_windowPtr;