void operator+= /ETHEntityArray

Appends a copy of the source array at the end of the destination array. Example:

ETHEntityArray orcs;
GetEntityArray("orc.ent", orcs);

ETHEntityArray elfs;
GetEntityArray("elf.ent", elfs);
ETHEntityArray soldiers;
soldiers += orcs;
soldiers += elfs;
// now the "soldiers" array holds all elf and orc handles

// Clears the "orcs" and "elfs" arrays but the "soldiers" array still stores the handles