runtime specification of output/input dirs

[edoyango]

output dir is currently hardcoded in param.f90

could be a commandline argument/option.

an input spec would come after the ability to read input files #4

[edoyango]

tried implementing an argument parser with FLAP. Implemented time-step specifications in 98d6eea, but have noticed that using FLAP with nvfortran produces issues - only the first two characters of each command line argument are being recognised.

e.g.,

$ ./a.out -s potato
 ./a.out has been called with the following argument: 
 String = po

Need to look into this a bit more.