[TravisCI] updated for dox upstream change.
Notice that it would still fail until this is merged: https://github.com/dpeek/dox/pull/77
[ci skip]
[TravisCI] Test -D js-flatten.
Respect 'extern' meta on abstract implementations, and avoid generating code for cpp.Object
[cpp] Order enums, and handle TFun enums. Ignore default values of null in scripting info