xaringanExtra 0.7.0

BREAKING CHANGE: All arguments to use_banner() must be named. use_banner()
now takes ... earlier since you may want to include style_banner() style
arguments without having to specify all the other arguments (#169).
scribble can now be disabled on an individual slide by adding
class: no-scribble to the slide (@mattwarkentin #166).
Embedding slides via embed_xaringan() no longer requires that you set
self_contained: false in the R Markdown document. embed_xaringan() now
automatically sets the data-external="1" attribute on the element embedding
the xaringan slides (thanks @jhelvy, @drfurtado, #177).
editable now hides remark's "Paused" overlay when editing slides in
presenter mode (#178).

Thanks!