Remove cluster nhits and energy members

They are only used in one place and not set anywhere else, so we just
use the values there rather than defining them as class members
Make StFmsEventClusterer members private

Only leave public what is needed externally
Add detector() method to return detector ID
Rename StFmsClusterFinder member

Change from pTowerUtil, which wasn't very meaningful.
Change from a pointer to an object, avoiding having to allocate and
delete
Delete nrows and ncols from StFmsEventClusterer

Not used for anything in our code
Remove NTower member from StFmsEventClusterer

Eliminate ntowers argument from FitEvent as the number can be determined
from the member tower list
Remove unused tow_Arr from StFmsEventClusterer
Remove arguments from FitEvent

Now just return true or false for a good or bad event, as the previous
arguments weren't really used for anything
Remove StFmsEventClusterer parameter members

Remove members that are just parameters used in a single place, and use
the stored values directly.

Small change in numerical values for points due to some changes from
float to double
Update StFmsEventClusterer naming

Change member and method naming in accordance with #18
Remove energy dependent correction function
Update StFmsClusterFinder naming

Change member and method naming in accordance with #18
Update StFmsClusterFitter naming

Change member and method naming in accordance with #18

Modify fit() and fit2PhotonCluster() behaviour so that
StFmsClusterFitter default steps are used if the steps argument is NULL.
This prevents having to expose the default steps publicly.