Manage freq in gmse_apply

[bradduthie]

A suggested enhancement by @jeremycusack is to get manage_freq to work in gmse_apply and effectively skip the management step when old_list is not NULL. The way that I would do this is to have an if statement in the main gmse_apply function that checks for the input manage_freq = -1 (negative one being easy to interpret). If that is the case and there is an old list with user costs in place, then management could be skipped, allowing for the manage_freq option currently restricted to the gmse function to also be used in gmse_apply.