Half a year after being pummeled at the polls, California egg farmers are squawking anew over what they call confusing directives in a measure passed in November that animal protection advocates say requires that chickens live cage-free. The Assn. of California Egg Farmers contends that Proposition 2 embraced the “broad principle” of giving egg-laying hens more space but failed to spell out how much. Debra J. Murdock, the group’s executive director, said in a letter sent Thursday to Ass