dirEntries depends on readdir, which has undefined order (eg: http://stackoverflow.com/questions/8977441/does-readdir-guarantee-an-order, and I've experienced as well dirEntries in non-alphabetical order)
shouldn't we make dirEntries return in alphabetical order by default, with an option to return in unspecified native order for efficiency? at least, it should be specified in doc that order is undefined.
