Start re-organizing demos so the physics setup can be shared easier (explicit create graphics objects, init/exit physics etc)

Add B3G_RETURN key code, only implemented in Windows so far (todo: Mac, Linux)
Fix Windows key management (use WM_CHAR event instead of WM_KEYUP
Add Return (OnKeyReturn) key support TreeNode, so we can select an item using the return key.

btgui/Gwen/Controls/TreeNode.cpp

@@ -132,6 +132,13 @@ void TreeNode::PostLayout( Skin::Base* /*skin*/ )
 void TreeNode::SetText( const UnicodeString& text ){ m_Title->SetText( text ); };
 void TreeNode::SetText( const String& text ){ m_Title->SetText( text ); };
 
+UnicodeString TreeNode::GetText() const
+{
+	UnicodeString bla = m_Title->GetText();
+	return bla;
+}
+
+
 void TreeNode::Open()
 {
 	m_InnerPanel->Show();