* Merged comment handling with the main loop of preprocessToDom(). This fixes a secti...

* Merged comment handling with the main loop of preprocessToDom(). This fixes a section numbering/marking regression introduced in r28588. Added parser tests demonstrating the issue.
* Merged includeonly/noinclude/onlyinclude handling with preprocessToDom(), and used the resulting überparser to fix another section numbering bug: bug 6563. The fix involves putting a template flag "T" into the section parameter of edit links. This flag indicates to extractSections() how <includeonly> etc. should be handled.

If these two changes stick, I'll eventually describe the precise syntactic effects in RELEASE-NOTES.

* Added splitExtNode() for future use in LabeledSectionTransclusion.
* Added parser tests for bug 6563.