Merge branch 'hakimel/master'

* hakimel/master: (1422 commits)
  tweak slides mention
  fix issues with overflowing fit-text when exporting to pdf hakimel#3191 hakimel#3120
  Fix typo in plugin.js
  notes plugin only listens for same-origin postmessages to prevent xss
  new attempt at speaker view xss fix
  add support for 'data-background-gradient' hakimel#2510
  fix issue where auto-animate did not work when jumping three or more slides (i.e. longer than the view distance)
  made data-background attribute work with .webp hakimel#3200
  fix: truncated long r-fit-text on pdf
  update link
  fix issue with hakimel#3182 when slide numbers are disabled
  fix inconsistent fragment visibility in looping presentations hakimel#3123
  fix: pdf page numbering for fragment group
  always use css transforms for presentation scaling (zoom has too many quirks even if it is slightly sharper on ldpi displays)
  update lock file
  4.3.1
  notes plugin allows messsages from current/upcoming slide windows
  fix hakimel#3154
  fix vertical slide link in demo hakimel#3155
  dont run full build + tests for package task hakimel#3156
  ...

.github/CONTRIBUTING.md

@@ -0,0 +1,21 @@
+## Contributing
+Please keep the [issue tracker](https://github.com/hakimel/reveal.js/issues) limited to **bug reports**.
+
+
+### General Questions and Support
+If you have questions about how to use reveal.js the best place to ask is in the [Discussions](https://github.com/hakimel/reveal.js/discussions). Anything that isn't a bug report should be posted as a dicussion instead.
+
+
+### Bug Reports
+When reporting a bug make sure to include information about which browser and operating system you are on as well as the necessary steps to reproduce the issue. If possible please include a link to a sample presentation where the bug can be tested.
+
+
+### Pull Requests
+- Should be submitted from a feature/topic branch (not your master)
+- Should follow the coding style of the file you work in, most importantly:
+  - Tabs to indent
+  - Single-quoted strings
+
+
+### Plugins
+Please do not submit plugins as pull requests. They should be maintained in their own separate repository. More information here: https://github.com/hakimel/reveal.js/wiki/Plugin-Guidelines

.github/FUNDING.yml

@@ -0,0 +1 @@
+github: [hakimel]

.github/workflows/js.yml

@@ -0,0 +1,24 @@
+name: tests
+
+on: [push]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        node-version: [10.x, 14.x, 16.x]
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Use Node.js ${{ matrix.node-version }}
+      uses: actions/setup-node@v1
+      with:
+        node-version: ${{ matrix.node-version }}
+    - run: npm install
+    - run: npm run build --if-present
+    - run: npm test
+      env:
+        CI: true

.gitignore

@@ -1,3 +1,8 @@
+.idea/
+*.iml
+*.iws
+*.eml
+out/
 .DS_Store
 .svn
 log/*.log

.npmignore

@@ -0,0 +1,7 @@
+/test
+/examples
+.github
+.gulpfile
+.sass-cache
+gulpfile.js
+CONTRIBUTING.md

LICENSE

@@ -1,4 +1,4 @@
-Copyright (C) 2014 Hakim El Hattab, http://hakim.se
+Copyright (C) 2011-2022 Hakim El Hattab, http://hakim.se, and reveal.js contributors
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal