fxied sampleModules not loading

* Rbuildignore had a (poorly-specified) rule to ignore `SAMPLE` directory
    - it also caused R to ignore the `sampleModules` dir, so it never was included
undo parts of Eliot's commit 27385bf

* path to diagrams is `../inst/doc/`
* vignette code should put outputs in tmpdir, and not modify the user's file system
rebuild intro vignette
clean up `colors.R` & docs
added rebuilt intor vignettte to inst/doc