Make some general changes to stats package where things either could have been better...

Make some general changes to stats package where things either could have been better or were just plain wrong.

statistics.hh:
fix a bug in binning that made bins a fixed size no matter what.  add GenBin class that is public but not templatized.
statistics.cc:
change map to statMap so others can use the map<> token without needing ::.  also, add a level of GenBin that is public base class for StatBin<>.

base/statistics.cc:
    change map to statMap so others can use the map<> token without needing ::.  also, add a level of GenBin that is public base class for StatBin<>.
base/statistics.hh:
    fix a bug in binning that made bins a fixed size no matter what.  add GenBin class that is public but not templatized.

--HG--
extra : convert_revision : 6976a891e414c9515cc5a613157f7cb86ef89008