Added an utility probability_map.combine [skip CI]
Added an utility probability_map.combine [skip CI]


Former-commit-id: 72ac19cb2016ffd57e7a8c16825c954e48090996 [formerly 8748f783f69c7833bd83c78bb81fd6ffe897f6b0] [formerly 8748f783f69c7833bd83c78bb81fd6ffe897f6b0 [formerly 94434403a1bf2417ff8c4e508adb8cf2e915818c]]
Former-commit-id: b93300f0512c8e4a84413ac9003fa0b618c4b936
Former-commit-id: 952a8d41ea9b52bf682785fe3b2e1815ca452e34
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine