[IMP]Working copy of promotions
[IMP]Changed to new stricture of rules
[IMP]
[IMP]on_change
[IMP]Completely working and tested
[ADD]1.Field for calculating number of times a promotion is called. 2.User Guide.
[REF]Code refactored. pylint improved. Note added for long function.
[IMP]User guide made more explanatory.
[IMP]PDF also modified.