DB: add HashSet maker, fix #168
DB: add HashSet maker, fix #168

lamfire/mapdb,olupas/MapDB,olupas/MapDB,pettermahlen/mapdb,codeaudit/mapdb,sumit784/mapdb,ffjiao/mapdb,ringoluo/mapdb,cocosli/mapdb,jankotek/MapDB,mebigfatguy/mapdb,morfeo8marc/mapdb,binarytemple/mapdb,hangum/mapdb,SleimanJneidi/mapdb,jankotek/MapDB,jankotek/mapdb,mebigfatguy/mapdb,jankotek/mapdb