mutation-testing

Right now the sphinx-apidoc results are part of the repo, but there's no real reason for that. We should be able to generate those docs on demand whenever we build the sphinx project.

The plugin source is currently split into two files, one of which is auto-generated by build.rs. The lib.rs is getting unwieldy. Time to browse for sets of functionality that can be put into their own modules, before navigating the source gets too cumbersome.

Right now the temp dir is deleted after running using a FS2 tempDir Resource. This is done in the MutantRunner.
It'd be nice to have a config option to keep the generated temp dir after running for debugging purposes to look

So a pattern I've seen a number of places in rust code (and have in my own code in places) is:

impl SomeStruct {
	pub fn new() -> Self {
	    Self::default()
    }
}

In cargo-mutants it will take this function and apply the Default mutagen to it creating code that is equivalent to the source code and then register as not caught. This could be solved by #[mutants::skip]