direct use of undefined changed to void 0
== undefined -> == null; fixes #642
Merge branch 'upstream' into tamed-undefined
Recompiled amber.
Merge branch 'upstream' into tamed-undefined

Conflicts:
	js/Compiler-Interpreter.js
Merge branch 'upstream' into tamed-undefined

Conflicts:
js/Compiler-Interpreter.js
Recompiled Test.js and CLI
Merge pull request #668 from herby/tamed-undefined

Tamed undefined