Use only enumerable properties#4

Open

piranna wants to merge 4 commits intoAVVS:masterfrom

SnowStormIO:master

Commits on Apr 4, 2016

Avoid replacing existing `toJSON` definitions.
coiscir
committed

Commits on Apr 5, 2016

Revise to exit module if `toJSON` is already defined.
coiscir
committed

Commits on Apr 6, 2018