Wallclock termination requires changes to params files of all problems

[ffoucart]

The newly implemented method to terminate the code after a given time, and allow checkpoint/restart without recompiling, will break existing problems unless new parameters are added to the params.input files:

//Name of files to store last checkpoint information
std::string restartFileName = "restartFileName.txt";
std::string restartFileTime = "restartFileTime.txt";

as well as the function

int timestepper::CheckWallClockTermination()

which can either return 0 (never terminate due to wallclock), or be copied from the torus.