Add render-related options to dataview sample

To more easily expose problems add options to the dataview sample
related to rendering of items (applying mostly to the MyListModel page
only):

* Use left/centre/right alignment (Ctrl+1/2/3)
* Use top/centre/bottom alignment (Ctrl+4/5/6)
* Toggle tall row usage (Ctrl+7)
* Toggle keep on using small wx logo, regardless of row size (Ctrl+8)
* Toggle multi-line text usage (Ctrl+9)

samples/dataview/mymodels.h

@@ -216,7 +216,7 @@ public:
         Col_Max
     };
 
-    MyListModel();
+    MyListModel(int modelFlags);
 
     // helper methods to change the model
 
@@ -310,3 +310,10 @@ private:
 
     wxDECLARE_NO_COPY_CLASS(MyIndexListModel);
 };
+
+enum ModelFlags
+{
+    MODEL_USE_TALL_ROWS = 1 << 0,
+    MODEL_KEEP_LOGO_SMALL = 1 << 1,
+    MODEL_USE_MULTI_LINE_TEXT = 1 << 2
+};