Trunk-4444 Validate order overlap with scheduled date

Comments:
In Order.java:
          - getCalculatedStartDate and getCalculatedEndDate are kept public for future use.
          - Can rename getCalculatedEndDate and getCalculatedStartDate with better names (if any).
I am quoting an example of the statement you have put. Let me know if unclear still.
                            Start Date            StopDate
Order1:               8/Aug/2014            11/Aug/2014
Order2:               5/Aug/2014              15/Aug/2014

But which part/comment you picked from the code is still unclear.