Use UMD pattern to support globals

This pattern supports CommonJS-like environment (Node), AMD, as well as
browser globals.

Using the returnExports UMD pattern (with no dependencies)

see https://github.com/umdjs/umd
UMD on trace aspect
Merge branch 'umd' of github.com:jasonkarns/meld
traceMeld
some fix for properties, but must be refactored
propertyDescription undefined chack