-- attackerPedia = string or nil
-- if string, add this text to the attacker unit type(s)
-- describe.txt entry created by civilopedia.lua
-- defenderPedia = string or nil
-- if string, add this text to the defender unit type(s)
-- describe.txt entry created by civilopedia.lua
-- attackerHelp = string or nil
-- if string, add this text to the attacker unit type(s)
-- help entry created by help.lua
-- attackerHelpActive = string or nil
-- if string, help.lua will attempt to check if this combat
-- modifier is active, and if so, add this text to the unit's
-- help entry generated by help.lua, instead of the text
-- provided by the attackerHelp field.
-- However, all functions of the form function(attacker,defender)
-- supplied in this combatModifier must be callable with the
-- nil as the argument for the 'defender' parameter.
-- Code will check if the attackerDetail is satisfied, and check
-- if customCheck(unit,nil) is true to see if this message should be
-- displayed.
-- Any functions provided as values for a combatSpec key
-- will be called with the attacker as the first argument, and nil
-- as the second argument.
-- defenderHelp = string or nil
-- if string, add this text to the defender unit type(s)
-- Help entry created by help.lua
-- defenderHelpActive = string or nil
-- if string, help.lua will attempt to check if this combat
-- modifier is active, and if so, add this text to the unit's
-- help entry generated by help.lua, instead of the text
-- provided by the defenderHelp field.
-- However, all functions of the form function(attacker,defender)
-- supplied in this combatModifier must be callable with
-- nil as the argument for the 'attacker' parameter.
-- Code will check if the defenderDetail is satisfied, and check
-- if customCheck(nil,unit) is true to see if this message should be
-- displayed.
-- Any functions provided as values for a combatSpec key
-- will be called with nil as the first argument, and the defender
-- as the second argument.