[birt-dev] Checkin: refactor some TOC related code

["Stanley Wang" <swang@xxxxxxxxxxx>]

Description:
Re-factor some TOC related code

Regression: Yes/No
No

Code Owner:
BIRT Engine Team

Code Reviewers:
Wei

Tests:
Unit test

Test Automated:  Yes/No
Yes

Branches Involved:
Birt

Files Changed:
engine/api/TOCNode.java

engine/executor/DataItemExecutor.java

engine/executor/ExtendedItemExecutor.java

engine/executor/GridItemExecutor.java

engine/executor/ImageItemExecutor.java

engine/executor/LabelItemExecutor.java

engine/executor/ListingItemExecutor.java

engine/executor/ListItemExecutor.java

engine/executor/MultilineItemExecutor.java

engine/executor/ReportItemExecutor.java

engine/executor/TableItemExecutor.java

engine/executor/TextItemExecutor.java

engine/toc/TOCBuilder.java

test/org/eclipse/birt/report/engine/api/impl/DataItemExecutor.java

test/org/eclipse/birt/report/engine/toc/TOCBuilderTest.java

Defect Entries Resolved:
None

Case Entries Resolved:
None

Notes to Developers:
None

Notes to QA:
None

Notes to Documentation:
None

Notes to Configuration Management:
None

Notes to Support:
None

Notes to Product Marketing:
None