Trac30220 use conditional on LO bookmarks

[mistmist]

This is rebased branch with one commit 2 years ago from Daniel Sikeler.

In contrast to https://github.com/WollMux/WollMux/pull/381 this one inserts conditions on bookmarks in the document.

The difference is that with this PR:

• the scenario with SibaLesSer.ott works
• the scenario with trac30220_bookmarkVisibility.odt fails

while with PR 381:

• the scenario with SibaLesSer.ott fails
• the scenario with trac30220_bookmarkVisibility.odt works

Now i don't know for sure which one of these is the "real" scenario that reflects actual usage, but i suspect it's the SibaLesSer.ott one, and the trac30220_bookmarkVisibility.odt was just created for easier testing with unmodified WollMux.

(plus the same javadoc fixes as in the other PR)