def initialize(options={})
      @color_scale = @data_bar = @icon_set = @formula = nil
      parse_options options
    end
Creates a new Conditional Formatting Rule object
@option options [Symbol] type The type of this formatting rule
@option options [Boolean] aboveAverage This is an aboveAverage rule
@option options [Boolean] bottom This is a bottom N rule.
@option options [Integer] dxfId The formatting id to apply to matches
@option options [Boolean] equalAverage Is the aboveAverage or belowAverage rule inclusive
@option options [Integer] priority The priority of the rule, 1 is highest
@option options [Symbol] operator Which operator to apply
@option options [String] text The value to apply a text operator against
@option options [Boolean] percent If a top/bottom N rule, evaluate as N% rather than N
@option options [Integer] rank If a top/bottom N rule, the value of N
@option options [Integer] stdDev The number of standard deviations above or below the average to match
@option options [Boolean] stopIfTrue Stop evaluating rules after this rule matches
@option options [Symbol]  timePeriod The time period in a date occuring... rule
@option options [String] formula The formula to match against in i.e. an equal rule. Use a [minimum, maximum] array for cellIs between/notBetween conditionals.