The original libraries that were a part of the Open Source Maps API Utility
Library have a "release" folder. This folder was meant to contain the latest
stable version of the library, so that a developer could refer to it and
automatically get updates without needing to change their script tag. The
concept of the release folder has been deprecated for various reasons:
  * Guaranteeing backwards compatibility limits innovation and refactoring.
  * Maintaining a release branch takes time, and time is hard to come by.
  * There isn't a thorough enough testing process for the library to guarantee
    that old functionality/behavior doesn't break. We can do much faster
    releases of new versions of a library if we're not concerned about
    exhaustively testing it.

So, please ignore the "release" folder and pick the numbered version that suits you. 
The versions are numbered chronologically, so it should be obvious which is the most
recent. Some libraries have a release_notes.txt with more info about the changes
across versions. If not, you can refer to the revision history in this project.