Simultaneous chiral separation of 3,4‐methylenedioxymethamphetamine (MDMA), 3‐4‐methylenedioxyamphetamine (MDA), 3,4‐methylenedioxyethylamphetamine (MDE), ephedrine, amphetamine and methamphetamine by capillary electrophoresis in uncoated and coated capillaries with native β‐cyclodextrin as the chir