BEPFrequency: make Solution1 static

I am tired of reading the cppcheck warning
SetCoverBenchmarker: disable hacky debugging output
main(): make CSV output tab-delimited

This makes it easier to read.
CsvWriter: print out a separator after the @prefix
main(): print example parameters (number of sets, etc.) in every CSV line
main(): Get the instance parameters (size, etc.) from the command line
main(): get the number of iterations on the cmd line.
SetCoverBenchmarker: return standard deviation, not variance
SetCoverBenchmarker: fix calculations of mean standard deviation

Previously, the program didn't divide by the number of samples and
instead returned an estimator of the standard deviation of the
population, not of the mean.