Update to reveal.js 4.1.2 (#136)

- New tools/ script to manually keep step for updates
- Plugins are all updated
- Template update following latest Pandoc version
- updated README for documentation
- Help page updated 
- See other change in NEWS file
diff --git a/inst/reveal.js-4.1.2/js/utils/constants.js b/inst/reveal.js-4.1.2/js/utils/constants.js
new file mode 100644
index 0000000..6c2382e
--- /dev/null
+++ b/inst/reveal.js-4.1.2/js/utils/constants.js
@@ -0,0 +1,10 @@
+
+export const SLIDES_SELECTOR = '.slides section';
+export const HORIZONTAL_SLIDES_SELECTOR = '.slides>section';
+export const VERTICAL_SLIDES_SELECTOR = '.slides>section.present>section';
+
+// Methods that may not be invoked via the postMessage API
+export const POST_MESSAGE_METHOD_BLACKLIST = /registerPlugin|registerKeyboardShortcut|addKeyBinding|addEventListener/;
+
+// Regex for retrieving the fragment style from a class attribute
+export const FRAGMENT_STYLE_REGEX = /fade-(down|up|right|left|out|in-then-out|in-then-semi-out)|semi-fade-out|current-visible|shrink|grow/;
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