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).
Could not run test generator for IntelliJ 13. It has an exception that says:
:57:43 PM PluginException: com/intellij/generatetestcases/ui/codeinsight/GenerateTestCasesConfigurable : Unsupported major.minor version 51.0 [Plugin: GenerateTestCases]: com/intellij/generatetestcases/ui/codeinsight/GenerateTestCasesConfigurable : Unsupported major.minor version 51.0 [Plugin: GenerateTestCases]