supporting same languages as highlight.js
IE 11 support

Added un-prefixed touch-action CSS attribute
added un-prefixed PointerEvents event handler hooks
IE11 Support

Added unprefixed touch-action CSS attribute
Added unprefixed pointer events handlers hooks
windows.navigator.pointerEnabled

for backward compatibility reasons, IE11 sets both msPointerEnabled and
pointerEnabled. Changed the order for the test and added 'else if' to
not duplicate handlers on pointer events
don't transition between identical backgrounds
fix edge case in background transitions (closes #604)
Added slide numbers options and the css files updated as well.

the *.min.js didn't chaged yet.
move the slide-number out of the controls to a proper position and little fix to the updating event.
synthetic fix
Removing global flag for replacing whitespaces
change SlidesNumber position and start page counter at 0 instead 1
generate background hash under additional conditions
add convex background transition
add concave and zoom background transitions
Add attributes in markdown for slide generation.

By default, look for <!-- slide-attributes: xxxx -->.
Whatever 'xxx' is will be added to the section attributes.

You can define your own pattern with 'data-attributes'.
For instance 'data-attributes="^\s*?-- (.*?)$"':
that will be added to the options.

The 'attributes' section is removed from the content of the slide,
so the final markdown doesn't reflect them.
That also means you can add those attributes *anywhere* in the slide

But that allows for *any* attribute to be added for a specifc slide,
like:

- id="plan", for allowing internal link (issue #430)
- data-background="#ff0000"
- data-transition="fade"

You list those attributes on a single line, like

- (default):
` <!-- id="plan" data-background="#ff0000" -->`
- or, with an alternative data-attributes pattern:
` -- id="plan" data-background="#ff0000"`

Again, that line is remove from the final content.
Fix bug on data attributes for first vertical slide.

The first slide of a vertical stack see some data attributes ignored.

Mainly the data-transition one.

Repeat all data-attributes on the wrapping section element.

Ignore any other attributes (like 'id="xxx"'), in order to not
mess with internal links (by repeating twice an id).
Make sure a pattern doesn't include space.
Fix markdown vertical wrapping section element generation.
Rebased on dev, and following contribution guideline.
Fix markdown.js slideAttributesSeparator selection.