Hcal 25ns constrained Method 2 for pre3

1. Fix the pulse shape used for MC to be number 105
2. If method 2 fails (nan issue) or not used (e.g., tstrig < ts4Min), it falls back now to Method 0
3. Add an option to control number of fit iterations
4. Separate out the hbheNegativeFlagSetter from the puCorrMethod switch. It was switched off when Method 1 was disabled. This hbheNegaviteFlagSetter is controlled by setNegativeFlags_ anyway.
5. Add print out to what method is actually activated
98.5 should become a const.
use std::abs() instead of fabs or abs (everywhere).
It would be good to add a comment explaining the formula(s) used.