HiBONT.remove

// remove
       auto hibon = HiBON();
       hibon["d"] = 4;
       hibon["b"] = 2;
       hibon["c"] = 3;
       hibon["a"] = 1;

       assert(hibon.hasMember("b"));
       hibon.remove("b");
       assert(!hibon.hasMember("b"));