Changed the onclick handler to trigger the impress:console:open event
and not use the impressConsole() global function any more. The latter
is considered deprecated now that impressConsole is integrated into
impress.js itself.
Also catch some errors that appear in event handlers when the target
for the click event was immediately removed from DOM.
Fixes#651
Add one presentation that provides a very simple demo, using
impress.js to create a very traditional "slide show". Possibly
it's an easier way to learn impress.js (it's commented, just like
the official demo.) It uses the relative positioning plugin and
uses "speaker notes", which aren't shown in the presentation,
but are picked up and shown in the speaker console (press 'P').
Also uses autoplay, forms... and includes short demo of all the extra
addons from extras/. (Highlight.js, Markdown.js, Mathjax.js, Mermaid.js)
