Check_MK Werk 5670: Handle history files from older EC versions, which have fewer columns.

ID: 5670 Title: Handle history files from older EC versions, which have fewer columns. Component: Event Console Level: 1 Class: Bug fix Version: 1.5.0i3 History files written by older versions of the EC might contain fewer columns than a newer EC handles. This fix fills these missing columns with their default values, avoiding log messages like unknown precedence '' in table eventconsolehistory in cmc.log later.