Fixed i_history in main to be int8. This caused problems before when trying to run greater than 2**31 - 1 particles per cycle.
Fixed i_history in main to be int8. This caused problems before when trying to run greater than 2**31 - 1 particles per cycle.

liangjg/openmc,johnnyliu27/openmc,smharper/openmc,amandalund/openmc,mit-crpg/openmc,lilulu/openmc,walshjon/openmc,lilulu/openmc,mit-crpg/openmc,smharper/openmc,sxds/opemmc,shikhar413/openmc,wbinventor/openmc,bhermanmit/openmc,bhermanmit/cdash,mjlong/openmc,amandalund/openmc,johnnyliu27/openmc,liangjg/openmc,kellyrowland/openmc,shenqicang/openmc,samuelshaner/openmc,nhorelik/openmc,smharper/openmc,wbinventor/openmc,amandalund/openmc,amandalund/openmc,samuelshaner/openmc,paulromano/openmc,paulromano/openmc,walshjon/openmc,samuelshaner/openmc,sxds/opemmc,mit-crpg/openmc,kellyrowland/openmc,keadyk/openmc_mg_prepush,mit-crpg/openmc,shikhar413/openmc,johnnyliu27/openmc,paulromano/openmc,johnnyliu27/openmc,walshjon/openmc,shikhar413/openmc,wbinventor/openmc,mjlong/openmc,samuelshaner/openmc,liangjg/openmc,lilulu/openmc,wbinventor/openmc,keadyk/openmc_mg_prepush,nhorelik/openmc,keadyk/openmc_mg_prepush,walshjon/openmc,shenqicang/openmc,shikhar413/openmc,smharper/openmc,paulromano/openmc,bhermanmit/openmc,liangjg/openmc