updated het_only flag to not require a reference allele.
trying to ignore changes in src/main/java/vtc/VTC.properties
test
test
updated SetOperator to treat 2/1 as a het and not allow 1/1 and 2/2 to intersect as homo alts. I also updated several test cases: Het_Or_Homo_Alt tests 1&2, Homo_Alt test1, and Het_Only test 2