added SCH and N1 Loops to the PO Details

Hello,

I am an EDI novice, but I did need to make some changes to the PO850 for my use-case. The changes include adding an SCH and N1 Loops to the PO Details. 

Can someone please comment if it is appropriate to merge these changes into the master branch? 

What is the correct way to validate there are no breaking changes?