Operator splitting, adaptive time stepping, and other fixes for mixing layer and bubbles #137

Job	Run time
Georgia Tech \| Phoenix (NVHPC) (cpu)	45m 30s
Github \| Docker	57m 56s
Georgia Tech \| Phoenix (NVHPC) (gpu)	28m 38s
Github (ubuntu, mpi, debug, true)	34m 42s
Github (ubuntu, mpi, debug, false)	1h 16m 51s
Github (ubuntu, mpi, no-debug, true)	1h 0m 32s
Github (ubuntu, mpi, no-debug, false)	58m 54s
Github (ubuntu, no-mpi, debug, true)	23m 29s
Github (ubuntu, no-mpi, debug, false)	17m 45s
Github (ubuntu, no-mpi, no-debug, true)	28m 36s
Github (ubuntu, no-mpi, no-debug, false)	18m 39s
Github (macos, mpi, debug, false)	55m 45s
Github (macos, mpi, no-debug, false)	1h 16m 50s
Github (macos, no-mpi, debug, false)	12m 52s
Github (macos, no-mpi, no-debug, false)	22m 53s
	10h 19m 52s

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