* Increment version number

* Better horizontal alignment of code blocks

* Use testthat 3e

* Use expect_known_output() because we need the css files

* Replace `with_mock()` with `mockery::stub()`

* Remove extraneous line

* Set ml and mr for all horiz alignment classes

* Add NEWS for #68

Avoids note for long argument length and allows for more consistent checking if supplied arguments are default values

style_* returns name of file invisibly

And add tests

Inspired by tachyons, easily add additional colors to slides using the `colors` argument. The argument takes a named list or vector and adds a CSS variable with the color name. Also added are .<color> and .bg-<name> classes.

* e.g. style_duo() <- duo()
* style_xaringan <- write_xaringan_theme()
* style_extra_css <- write_extra_css()
* added NEWS entry
* updated docs and /docs