Better SMPP delivery receipt detection and general refactoring of DR handling.
Better delivery report handling and configurable status value mapping.
Better comment.
Merge branch 'develop' into feature/issue-637-smpp-delivery-receipt-params
Merge branch 'develop' into feature/issue-637-smpp-delivery-receipt-params
Merge branch 'develop' into feature/issue-637-smpp-delivery-receipt-params
Merge branch 'feature/issue-637-smpp-delivery-receipt-params' into develop