Added sequenceNum to ProductFeatureGroupAppl

Hi

I have added a sequenceNum field to the ProductFeatureGroupAppl entity, and updated the EditFeatureGroupAppls.bsh to load the sequenceNum's when using:

Product>Features>Add Product Feature From Category or Group>

This way if a group of features always need to be sorted the same way you don't need to enter the sequence every time you add the feature group to a product.

Also see:
http://lists.ofbiz.org/pipermail/dev/2006-June/011325.html