Problem: zpl code is not a part of unit test
Problem: zpl code is not a part of unit test

Solution: test _zpl and _new_zpl as part of unit test. Fixes some issues
in code.

vyskocilm/zproto,bkmit/zproto,jdiez17/zproto,zeromq/zproto,zeromq/zproto,bkmit/zproto,jdiez17/zproto,zeromq/zproto,somdoron/zproto,zeromq/zproto,jdiez17/zproto,sappo/zproto,bkmit/zproto,bkmit/zproto,vyskocilm/zproto,vyskocilm/zproto,vyskocilm/zproto,jdiez17/zproto,sappo/zproto,somdoron/zproto,somdoron/zproto,sappo/zproto,zeromq/zproto,jdiez17/zproto,somdoron/zproto,vyskocilm/zproto,sappo/zproto,bkmit/zproto,zeromq/zproto,somdoron/zproto,sappo/zproto,zeromq/zproto,vyskocilm/zproto,bkmit/zproto,jdiez17/zproto,sappo/zproto,bkmit/zproto,somdoron/zproto,jdiez17/zproto,sappo/zproto,somdoron/zproto,vyskocilm/zproto