Made nextStep and previousStep functions publicly accessible
Added missing commas
Add checkpoints to intro.js

Enable programmer to define which steps are checkpoints. I.e.
prevent the user from going back after certain steps. This is
useful if the user will be changing the state of the system
(creating a database entry, etc.) so the user doesn't go
back and redo their change.
Fix stacking context bug caused by opacity
Calling exit() on null issue solved
readme update: add where-to-get section
added onafterchange method, and call it just before the end of _showElement method

difference with onchange is that onchange is executed first time upon entering _showElement method. This will fail if we want to, for example, set focus to the current input element being shown, because the element is modified in _showElement method. onafterchange is executed just before the end of _showElement method, so any changes to the current element will persist. I found this especially useful when trying to set focus to an input element which is currently being intro-ed using jquery's .focus().
Do not add top marging if step numbers are hidden
Allow scolling to element to be set as option

* Auto-scrolling isn't always the user experience you want. Allow it to
 be turned off.
be robust against complex rerendering/updating of the addressed DOM node by any application user code: prevent crash when introJS class tweak is already gone.
Revert "properly correct the CSS to show the red number per tooltip: now the red circle is bigger and fits each number easily."

This reverts commit 6e64d8c87a3062c51c81b15fb76b276275efb25e.

That commit changed the red number styling to suit my browsers but for some unidentified reason all browsers were rendering incorrectly - the next night, after a complete machine crash (hardware freeze) and reboot the edited styling is wrong, as it was on a freind's machine (OS/X) -- for which I had no explanation at the time. Apparently something very odd happened on the local dev box there.
- added preliminary example to showcase custom actions when overlay is clicked.

- user callbacks introExitCallback and introCompleteCallback now are called with a 'reason' parameter, which is an object containing information about which action/event triggered the callback.

- always call _exitIntro() AFTER the user callbacks have been invoked: hence _exitIntro is the very last action performed by IntroJS when the demonstration terminates.
Added method _cloneObject

Added method _cloneObject makes a copy of the settings, that data is not overwritten.
completed the Makefile to detect and run `npm install` when necessary for the success of the build process.

Also added the Makefile targets 'clean' and 'superclean' (naming and intent mimicking these targets for any GNU autotools project: 'superclean' blows away the entire npm install set and thus ensures the next `make` build will create a completely fresh output.
ignore all minified files: those are output of the Makefile build process
Add donation button
Update index.html

typo and RTL definition
fix issue with single-step pages (closes #229)

* Fixes issue with "Done" label not shown on pages with a single
data-step.

Signed-off-by: Adrian-Tudor Panescu <adrian.tudor.panescu@cern.ch>
buttons tweaks

* Next button will not be displayed when no next step exists.

Signed-off-by: Adrian-Tudor Panescu <adrian.tudor.panescu@cern.ch>
updated Makefile to help build the package, including automatic npm install of prerequisites