when adding a month to a month with fewer days, overflowed into next month

when adding a month to a month with fewer days, overflowed into next month
Fix placed here will ensure that if the result month has fewer days
the months are still calculated as a month addition and not a number of days.

A24Group/Triage#5145
updated comments

updated comments

A24Group/Triage#5145
updates as per comments

updates as per comments

A24Group/Triage#5145
Merge pull request #231 from A24Group/bugfix-Feb-date-calc-5145

when adding a month to a month with fewer days, overflowed into next month