* First version of preprocessor example, with quicli
It seems it's not worth it right now.
* Remove quicli, just to simplify everything
* Finish de-emphasise example
* Finish preprocessor example in book
* Rename preprocessor type
* Apply changes requested in review
* Update preprocessor docs with latest code
[skip CI]
* Added documentation to the `config` module
* Added an example to the `config` module
* Updated the docs in lib.rs regarding implementing backends
* Started writing an alternate backends walkthrough
* Mentioned the output.foo.command key
* Added example output
* Added a config section to the backends tutorial
* Finished off the backends tutorial
* Made sure travis checks mdbook-wordcount
* Fixed the broken link at in the user guide
* Changed how travis builds the project
* Added a conclusion
* Went through and documented a lot of stuff
* Added a preprocessors chapter and updated For Developers
Michael Bryan
Ramon Buckland
Matt Ickstadt
Sebastian Thiel