Those who thought Urinetown would be the most irreverent musical to hit the D.C. area never bargained for Cannibal! Landless Theatre Company’s latest production (clearly to some degree a satire of Oklahoma!, as its “Shpadoinkle Day” number can only be a send-up of “Oh, What A Beautiful Morning!”) follows the unassuming Alferd Packer, who leads a motley crew of gold-seekers into the mountains, where they are met with less-than-desireable circumstances, from a mythical Cyclops to,…