Messages text chaged: gSOP -> SOP-GPU
Fixing bug in argc checking in main.cpp
Numerous minor changes

Mostly in Integrators/langevin and Updaters/output_manager
Fixing minor typo in Potentials/indentation.cu
Removing fflush before fclose

Because it's unnecessary
Fixing introduced error in Updaters/output_manager
Removed unnecessary memory allocation in gsop.cu
Separated ran2