This patch solves this crash (due to an assertion):

This patch solves this crash (due to an assertion):
1) Open EmbeddedObject.lyx
2) Open Toc
3) Click on section 7.2.2 which is in the second child document
4) assertion.

This commit adds proper support for multi-part documents. With this each child document has access to the _full_ TOC tree (including LOT and LOF). This enables to switch between master and child document using the TOC.

* buffer_funcs.cpp:
  - updateLabels(): do not emit Buffer::structureChanged() signal for child document
  - checkBufferStructure(): update the structure of the master document.

* ControlToc.cpp: always use the TocBackend of the master document.

* LyXView::connectBuffer(): connect structureChanged() of master document.

* TocBackend:
  - TocItem: get rid of child_ member.
  - TocBackend::item(): only compare items from the same document.

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@18386 a592a061-630c-0410-9148-cb99ea01b6c8