Urgent bug fix release for JS.Class 1.6

Quick announcement: if you’re still running JS.Class 1.6, you’ll want to upgrade to the just-released 1.6.3 release which fixes a major bug introduced by Safari 4. This browser makes Function#prototype non-enumerable until it is overwritten by the user. This caused a check in JS.Class to fail, causing classes to become their own parents and cause stack overflows. Head over to the JS.Class website to download the latest version.