Fix summation(k, (k, 0, oo)) == nan, should be oo
Implement is_positive handler for factorial (partial fix for issue 1072)
Cleanup eval_sum_hyper()
Fix issue 1072
Merge pull request #2310 from skirpichev/1072-infinite-sums

Fix issue 1072
n*m is even if n+m is odd (old assumptions)
n*m is even if n+m is odd (new assumptions)
UnXFAIL Wester test_H3