HOUSTON/NEW YORK (Reuters) - Private equity firm Kimmeridge Energy Management Co said on Thursday it had boosted its stake in Carrizo Oil & Gas Inc (CRZO.O) by more than 65 percent and wants the U.S. shale producer to sell assets or combine with a rival to boost its share price. The move comes as investors have grown increasingly fed up with the U.S. shale industry’s spendthrift ways and are pushing producers to improve shareholder returns and focus less on output. “Our goal is essentially to...