A time bomb that could bring major changes to California politics has been set in place and is very likely to become explosive before the next presidential election. Right now, Democrats are licking their chops over the potential benefits they expect from same-day voter registration, a practice that’s been allowed in nine other states and will become the norm here the year after the secretary of state, California’s top election official, certifies a new high-tech voter registration database. That will take several more years but most likely will be done before the fall of 2016. Same-day registration is a system …