Used to render out all informal parameters, at the end of the 
BeginRender
 phase.
 This mixin can be used with components that render a single tag inside the 
BeginRender phase. RenderInformals
 will activate during the PostBeginRender phase to write additional attributes, from the informal parameters, into the
 active element.
 If you want this behavior, but need to render more than a single tag, then implement render phase methods for the
 
BeforeRenderTemplate and 
AfterRenderTemplate phases. Use those phases to write the additional
 elements and close them.
 This is often used as a base class, for cases where a component doesn't have other mixins.