[18Ardennes] Allow the GL to be sold when in EMR

Fixes #137.

lib/engine/game/g_18_ardennes/entities.rb

@@ -454,6 +454,10 @@ def buyable_bank_owned_companies
           @round.operating? ? [] : super
         end
 
+        def company_sale_price(company)
+          company.value
+        end
+
         # Has the player won any auctions for public companies in the
         # preceding auction round? If they have then they must start these
         # majors before they can buy any other shares or pass.

lib/engine/game/g_18_ardennes/step/buy_train.rb

@@ -7,11 +7,37 @@ module Game
     module G18Ardennes
       module Step
         class BuyTrain < Engine::Step::BuyTrain
+          def actions(entity)
+            actions = super
+            actions << 'sell_company' if actions.include?('sell_shares') &&
+                                         can_sell_any_companies?(entity)
+            actions
+          end
+
           def train_variant_helper(train, entity)
             return super if @game.can_buy_4d?(entity)
 
             super.reject { |v| v[:name] == '4D' }
           end
+
+          def process_sell_company(action)
+            player = action.entity
+            company = action.company
+            price = company.value
+            company.owner = @game.bank
+            player.companies.delete(company)
+            @game.bank.spend(price, player)
+            @log << "#{player.name} sells #{company.name} to bank for #{@game.format_currency(price)}"
+          end
+
+          private
+
+          def can_sell_any_companies?(entity)
+            player = entity.owner
+            return false unless player&.player?
+
+            !player.companies.select { |c| c.type == :minor }.empty?
+          end
         end
       end
     end