FastSimulation/L1CaloTriggerProducer: Resolve a number of Clang issues

This solves a number of issues reported as Clang errors and warnings. Also at least 3 Clang Static Analyzer reports are resolved.

This package badly needs cleanup.

Review the changes!
for my education
why do we need this change?
and what would be wrong with the more traditional
for(unsigned int i = 0;i<16;i++)