first step of currently countless other to update the UserGuide.lyx

first step of currently countless other to update the UserGuide.lyx
Changelog:
(I'll announce a list of changes on the lyx-docs list for the translators when the update is ready)

- index generation: sec. 6.6, 6.6.3, 6.6.5
- wrap floats: sec. 4.6.1.4
- new horizontal space dialog: complete sec. 3.5, sec. 3.5.6 is now sec. 3.5.2
- new hyperlink dialog: Bibliography

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@23802 a592a061-630c-0410-9148-cb99ea01b6c8