Feat/debug things

[gwillz]

When inspecting a page we often tack on a <!-- path/to/template --> comment to help us find our way around. So this does it automatically (within non-production) for each view render.

This PR also has a fatal error handler. It's not something we see a lot of, but it makes prettier error pages of compiling or input errors.

I probably want this in the v3.3 release but I'm twitchy about it for some reason. Any thoughts?

[gwillz]

bump?

[gwillz]

before

after (dev)

after (prod)