new methods added to Job to check the state of the requiredParts
new methods and attributes added to Order to get the order components and the assembly components. minor clean-up

Conflicts:
	dream/simulation/OrderComponent.py
new ConditionalBuffer that complies with the requirements of the required parts
new MouldAssemblyBuffer inheriting from the ConditionalBuffer
new MouldAssembly inheriting from MachineJobShop