Render class should have callbacks or a way to set the queue beyond processing instructions

[brendanmetzger]

...that is, the processing instruction is a queue of renders that can be called or specified elsewhere. The thinking here is that if you have a controller or special class that wants to modify a template automatically, then it can just pop something into the render queue.

Consider that there may need to be a before & after queue, as there is stuff that might be worth doing as soon as the document is loaded, such as setting the template paths in the interface for editing.

[brendanmetzger]

Logging should be a type of dynamic render, think of using something like the benchmark class

Admin mode should be a dynamic render