File > Example menu should make sketchbook library overrides apparent

Arduino provides a powerful feature for users to override any library, by simply placing a copy in their sketchbook libraries folder, which is typically Documents/Arduino/libraries.

Sometimes users do this to solve a problem, or by following steps on a website or tutorial, and then later (months, years...) forget they've got a copy installed there. Sometimes they're not even aware this will override any other library with the same name.

In Arduino 1.6.3, we added messages when compiling, to advise users of conflicts, with specific info about which copy of the library Arduino is using and which others it's ignoring. That mostly solved the worst troubles.

However, the File > Examples menu doesn't clearly show users they've overridden a built-in or custom library. This can be terribly confusing when a user doesn't realize they long-ago put a copy in that location. For example, here's a recent forum conversation which took several replies to resolve.

https://forum.pjrc.com/threads/33185-Audio-Library-examples-issue

I know the presentation in Arduino's GUI is a sensitive issue. I'm hoping we can consider adding info to the File > Examples menu to specifically show users when one of their sketchbook libraries is overriding any other library. I'm willing to work on a patch, and I'm looking for feedback regarding what sort of changes to the menu would be acceptable for Arduino?

Start with the File > Examples menu behavior described in the issue and review the linked forum conversation for the reported confusion. Determine an acceptable way to indicate when a sketchbook library overrides another library; done means affected menu entries clearly expose that override without making the GUI presentation unacceptable.

Written by the indexing model from the issue text.