Properly accumulate splits (bug #165053).

[Derek Atkins]

Log Message:
-----------
Properly accumulate splits (bug #165053).  

	* src/business/business-core/gncInvoice.c: Properly accumulate
	  splits (bug #165053).  Also fixes a (related) memory leak
	  (caused by the same lack-of-reference to accumulated splits).

Tags:
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gnucash-1-8-branch

Modified Files:
--------------
    gnucash:
        ChangeLog
    gnucash/src/business/business-core:
        gncInvoice.c