New HOC api

[willybrauner]

• create HOC to manage mount & unmount component automatically via useIsMount()

// Create now an external instance :
export const HeaderTransitionsManager = new TransitionsManager()

// component using transitions manager 
const Header = () => 
{
// ...
}
export default TransitionsHoc(Header, HeaderTransitionsManager)

• auMountUnmount option is now true by default
• add unit tests