fourth order OMF integrator added with input key OMF4
Merge branch 'master' into omf4
Merge remote branch 'upstream/master' into omf4
Merge branch 'master', remote-tracking branch 'origin' into omf4
renamed file-global variables and declared static
Merge pull request #170 from urbach/omf4

fourth order OMF integrator added with input key OMF4