Improve section about handout
Allow frame breaks
Improve (and add) contents
Updating "authoring presentations"
Reorganize slides around "customizing presentations"
Improve (support of) R blocks
Fix section "Inline LaTeX" and many other details
Reindent blocks so that they become independent frames
Improve sections about blocks
Fix most of block environments
Add blocks of different size and style
Improve BEAMER_act property
Add shorter notation for export snippets