Don't confuse index of scalers with slot number

See https://github.com/JeffersonLab/analyzer/commit/cd7c26b5b1161115a0e35a4824148b78a189e986

NOTE:
This changes the format of the "variable" lines in the db map file that
defines the scaler layout.

The number after the variable directive is now the slot number instead of
the index of which scaler module (starting from zero) is being used.
Updated DBASE/db_PScalevt.dat and DBASE/db_HScalevt.dat files which have
been generated by an updated MAPS/SCALERS/make_scaler_db.py.  This change is
made so that the "variable" line format is the same as used in
THaScalerEvtHandler.cxx.