PowerPoint: Change Language in whole Presentation (VBA Macro)

See updated version.
Working in an international environment, I need a lot of time to fix the language in a whole PowerPoint presentation. There is no built-in feature for this available. I share here my VBA based solution.

Current situation

There are some commercial Add-Ins to achieve this. See for example: AddIn Lingo by PPTAlchemy to buy for 30USD (as of 2016-06-28).

I didn't want to pay for this. I looked for a solution in StackOverflow. (see references)

VBA Code

At the end I came to this VBA solution:
This feature is available in my PowerPoint Add-In (available in GitHub).

References

PowerPoint-2007-set-language-on-tables-charts-etc-that-contains-text (StackOverflow)

VBA PowerPoint 2013: Change presentation language including smartart objects (StackOverflow) 

PowerPoint 2007: Set-language for all text/

Updated: PowerPoint: Change Presentation or Selected Slides Language | Thierry Dalon's Blog