0.4.0

• Upgrade frontend dependencies to ^0.2 (https://github.com/BosonPHP/frontend/releases/tag/0.2.0)
• Added binary compat constraints.
• Added Window::restore() method (restores window state after maximize/minimize).
• Fixed and improved Window min, max and size properties initialization logic.
• Fixed Window::maximize() method behaviour.
• Added WindowDecorationChanged event (after window decoration has been changed).
• Added WindowStateChanged event (after window state has been changed).
• Added Window::$state property (read only) and WindowState enum:

enum WindowState
{
    case Normal;
    case Minimized;
    case Maximized;
}