Add BATCHES= environment variable to overwrite # of batches for GMLS problems

[kuberry]

In the GMLS generateAlphas() call, look for environment variable BATCHES and overwrite the # of batches requested if specified. Because a true/false flag follows in the argument list for the function, this will fail if batches>1 for a call where polynomial coefficients were to be retained (which is fine). However, for problems where the polynomial coefficients do not need to be retained, this gives the user much greater runtime flexibility.