Other optimizers

Hi Tim,

in preparation for the Fisher method, I've put the scanning method back in place, but in a completely separate module. I've also split the "optimizer method" (i.e. bfgs minimizer, scan or fisher) from the metric/statistics (i.e. chi2 or LLR). This way, we'll also have the chance to run Chi2-scans or LLH scans, or run the optimizer with a chi2 metric, etc...

This one also has the directories for the Fisher analysis, but they are currently empty.