add (failing) test
do not export properties starting with "_" from exported classes (unless requested explicitly)
do not mangle exported static variables
[refactor] do not create unnecessary function to represent a class, only create the ctors and use one of them in "instanceof", etc
update esmangle (fixes https://github.com/Constellation/esmangle/issues/71 t/run/043.Number.jsx)
add failing test
avoid exported names when minifying static variable names