parameter set multile inheritance does not work when N is > 1

[info-rchitect]

Hi,

The following spec test will result in missing inherited parameters (:a and :b).

    it "mutiple inheritance works" do
      class IP4
        include Origen::Model

        def initialize
          define_params :a do |params|
            params.a = 20
            params.b = 11
            params.tm.a = 1
          end

          define_params :b do |params|
            params.a = 30
            params.c = 22
            params.tm.b = 1
          end

          define_params :c1, inherit: [:a, :b] do |params|
          end

          define_params :c2, inherit: [:b, :a] do |params|
          end

          define_params :c3, inherit: [:a, :b] do |params, parents|
            params.a = 40
            params.d = 33
            params.e = parents[:a].a + parents[:b].a
          end
        end
      end
    end

The parameter tm.a is missing from the c3 parameter set.

[info-rchitect]

PR created

[info-rchitect]

#360