Final report: ODF Improvements

Hi!

This is brief report of ODF improvements GSoC project. So here is list
of things that I've done during GSoC:

1. Added support for titles in hyperlinks to Abiword and ODF
exporter/importer (accessibility feature similar to "title" attribute
in HTML)

2. Improved way we set modified and created date for all exporters.
Before the fix we had to set these values in each exporter separately.
Because of it many of exporters had similar bug: they had assumption
that values are already set and exported empty strings. Now these
values are set up before each export action automatically.

3. Added support for "text:note-citation" to ODF importer. Before it
some ODF documents that used this attributes in footnotes caused
difference in footnotes number between original and imported file
because Abiword supports only through numeration. Currently we can
handle such documents. But we need to decide if Abiword should expose
such feature to users(it handled internally at the moment and user
can't set such kind of numeration explicitly).

4. Fixed bugs:
- 12388
- 12628
- 13327
- 12296
- 12397
- Added handler disconnection code to avoid incorrect dialog answer
while inserting field (was not in the bugtracker)
- 12522
- 12789
- 12725
- 12726
- Fixed reason of some silent crashes on import (was not in the bug tracker)
- Fixed issue in ODF exporter that caused generation of invalid ODT
documents in some specific cases(like paragraphs nested into tables)

Also there were several changes that fixed some of math import/export
issues but then there were conflicting with math import/export
improving project, so I didn't commit them.

5. Added delayed writing of paragraphs in ODF exporter that allowed to
handle styles more properly(in addition to existing delayed paragraph
content exporting).
6. Some minor refactoring to improve readability, fixed several names
of variables according to general naming conventions
7. Ported most of importer code to std::string instead of
UT_UTF8String and tested it.
8. Introduced several new features:

- thumbnails support in ODF exporter
- import of ODF soft page-breaks
- new file path field (short file name instead of full path)
- last changed field import
- some ODF documents can contain nested empty lists in which only the
last list contains data. Added support of "collapsing" such lists on
import to a single list with corresponding style.

9. Added additional checks in field handling code to prevent silent
crashes on import.

Best wishes,
Tanya