[Cleanup] Add Updaters class

src/adaptivetimestepper.hh

src/coupledtimestepper.cc

src/coupledtimestepper.hh

src/coupledtimestepper_tmpl.cc

src/fixedpointiterator.cc

src/fixedpointiterator.hh

src/fixedpointiterator_tmpl.cc

src/sand-wedge.cc

src/updaters.hh