Header information for number of events

what the title says

assigned to @jschumann

added 10 commits

• 15536e9b...5a91019b - 9 commits from branch master
• 7317d9d5 - Individual field for GiBUU events and true number of gen file events to genvol

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added 1 commit

• 09cb64f7 - yapf

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added 1 commit

• 15a32e05 - Fix header setline as it only accepts strings

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added 1 commit

• 3ae8f8a2 - Add write out of event number for NoVolume

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added 1 commit

• 2ad9c897 - yapf

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added 2 commits

• 019ff080 - Add test for header
• 44ce18ef - Split info about n_files and n_gen

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added 2 commits

• 6a2bd7e7 - Split info about n_files and n_gen
• 841af46e - add tests

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enabled an automatic merge when the pipeline for 841af46e succeeds

mentioned in commit 34c1381d

merged