Making the default template rendering editable from system designers' pov

[AlexBoyd]

• [x] Refactor out logic that is currently doing a lot of inline template rendering into explict prototype template files.
• [x] ~~Use these prototypes for generating the default screens.~~
• [x] Load the prototype template file if template file isn't present in the screen
• [x] use implicit "phantom" screens even if none no screens exist that load the prototype tempates
• [x] Figure out solution for existing screens in the wild that do not contain a duplicate of the default template.
• [x] convert list templates to same pattern.
• [x] convert table generation to use templates.
• [ ] clean up code in default templates?
• [ ] Decide to universally rely on templates (as in the top / bottom cases) or keep a default code equivalent (as in the list / table cases)
• [ ] convert top and bottom templates in the multi page screens.

[AlexBoyd]

Only issues I could fine while testing were related to the lack of bottom template on the file system. I don't have any coverage on what sort of templates are being used out in the wild though so some attention should be put on watching this when it goes out to the wider public on the next major release.

[AlexBoyd]

When looking through the list templates rendering as reference for the multi page equivalent, found a fatal flaw in the way I tested this. It must have not been correctly using the template. Unfortunately this means that the list template rendering needs more work.