Split single/multi line behaviour in Qt wxTextCtrl

Introduce wxQtEdit class and wxQtMultiLineEdit and wxQtSingleLineEdit
derived classes instead of using ifs in many wxTextCtrl methods, making
the code more clear and maintainable.

Also fix some wxTextCtrl-related unit test failures with wxQt and
disable some other ones which still don't pass.

Closes https://github.com/wxWidgets/wxWidgets/pull/1039

include/wx/qt/textctrl.h

@@ -8,9 +8,8 @@
 #ifndef _WX_QT_TEXTCTRL_H_
 #define _WX_QT_TEXTCTRL_H_
 
-class QLineEdit;
-class QTextEdit;
 class QScrollArea;
+class wxQtEdit;
 
 class WXDLLIMPEXP_CORE wxTextCtrl : public wxTextCtrlBase
 {
@@ -25,6 +24,8 @@ public:
                const wxValidator& validator = wxDefaultValidator,
                const wxString &name = wxTextCtrlNameStr);
 
+    virtual ~wxTextCtrl();
+
     bool Create(wxWindow *parent,
                 wxWindowID id,
                 const wxString &value = wxEmptyString,
@@ -71,8 +72,7 @@ protected:
     virtual QScrollArea *QtGetScrollBarsContainer() const;
 
 private:
-    QLineEdit *m_qtLineEdit;
-    QTextEdit *m_qtTextEdit;
+    wxQtEdit *m_qtEdit;
 
     wxDECLARE_DYNAMIC_CLASS( wxTextCtrl );
 };