Porting 5_3_X HI reco updates to 7_2_X

The HI RECO updates that were previously implemented in 5_3_X are re-implemented in 7_2_X.

Indentation in this file is already quite profuse.
The methods shouldn't be indented even further.
Please align to the left (diff -b or similar can be used to compare with previous versions of the file)