The reason for this change is that I was informed by a community
member that the Pro Micro board does not have the default pin 13. This
causes many issues for beginners that are not familiar with the inner
workings of the library. However, I am concerned about this being a
breaking change. If there are serious issues I may just end up adding
a tutorial in the FAQ for beginners, informing them how they may
change the default pins.

This reverts commit 20a4d97, reversing
changes made to 47aadf5.

Credits: https://github.com/LarsWH
Excerpt from PR:
```
Hi,

I added support for 'RC5 extended' in order to make this project:
https://www.instructables.com/id/Remote-Control-for-Lava-mMotion-Swing-Mounting-Bra/

The modification is working nicely in this single application. It has
not been tested elsewhere.

(I am new to Git and this is my first pull request ever. So please
excuse me if I have messed something up)

Kind regards,
Lars
```

Merged #522