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
* when nmeas < nsave, nstore is not incremented from run to run and exactly the same random numbers will be used from run to run
* also, trajectory_counter is normally initialized to 1 but it was set to 0 if initialstorecounter was set to "readin" but
no .nstore_counter file was present, this commit makes the two self-consistent
Merge pull request #257 from kostrzewa/seed_xor_trajcounter

fix for random seed XOR and initialization of trajectory_counter
Add multiple I/O attempts on failure instead of immediate abort.
Use kill_with_error on I/O failure. Fix missing ifdef on MPI barrier.
Merge pull request #249 from deuzeman/io_retry

Add multiple I/O attempts on failure instead of immediate abort.
Merge pull request #170 from urbach/omf4

fourth order OMF integrator added with input key OMF4