By Alex DobuzinskisLOS ANGELES, Dec 30 (Reuters) - After a decades-long campaign to legalize marijuana hit a high mark in 2012 with victories in Washington state and Colorado, its energized and deep-pocketed backers are mapping out a strategy for the next round of ballot-box battles.They have their sights set on possible ballot measures in 2014 or 2016 in states such as California and Oregon, whic