Bugfixes relating to converting estimate into workshop job

• Make sure parts are added to job in same order they are on the estimate
• Subtle bug on import estimate means parts will be added with wrong retail price but will have discount set to compensate.  Consider two parts:  Part a $100. PArt b$20.  Part A would be added correctly. But Part B would be added at $100 less $80 discount.  Now fixed.