Improved drastically UIBorderDrawable performance.
Added Event::OnItemValueChange event and ItemValueEvent.
Added i18n function to UIWidget.
Remamed Node::addMouseClickListener to Node::onClick.
Added UI_SCROLLABLE flag and UINode::isScrollable to indicate if the widget implements some scrolling function and now UIScrollView will check if it can scroll by checking if the widget over is scrollable or not.
UISceneNode now implements loadLayoutFromString with const char* to avoid unnecessary std::string allocations.
Several fixes in UIListBox and UIDropDownList.
ecode:
Continued working on UIBuildSettings screen and Project Build configuration.
