* The preprocessor trait now returns a modified book instead of editing in place
* A preprocessor is told which render it's running for
* Made sure preprocessors get their renderer's name
* Users can now manually specify whether a preprocessor should run for a renderer
* You can normally use default preprocessors by default
* Got my logic around the wrong way
* Fixed the `build.use-default-preprocessors` flag
lzutao
Dylan DPC
Michael Bryan