Resolves issue when editing existing text in SimpleMultilineEntryElem…

…ent. Previously tapping in existing text would allow a single character to be inserted before insertion point would jump to end of text. Solution derived from http://stackoverflow.com/a/13394838/132599 answer.  Patch from @daveclarke

ElementPack/SimpleMultilineEntryElement.cs

@@ -256,11 +256,15 @@ public void FetchValue ()
 			var newValue = entry.Text;
 			if (newValue == Value)
 				return;
-
+
+			var currentPos = entry.SelectedRange.Location;	
 			Value = newValue;
 
 			if (Changed != null)
 				Changed (this, EventArgs.Empty);
+
+			if (currentPos > 0)
+				entry.SelectedRange = new NSRange(currentPos, 0);
 		}
 
 		protected override void Dispose (bool disposing)