I love this app, but it looks like there is no longer a free Mac version, however there is a portable java version.
I took the 4.2 app, and copied in all of the files from the portable version into the app package, and the missing libraries, and I was able to get a working 4.5 version.
It's a great app, but sad that there is no longer a free Mac version. It is free on every other platform, but on Mac, they make you buy it from the app store.