Do not use 'unsafe' tipa shortcuts

Turns out they are, well, unsafe (i.e. conflict with existing 'core' macros).
Fix string (patch by Jean-Pierre Chretien)
de.po
Localize 'Export As...' dialog
de.po
Fix 'Export As...' in non-English localizations

It is always a bad idea to compare a localized string. I think the whole method Formats::getFormatFromPrettyName (which is now unused) should be ditched. This is bound to fail.
* sk.po
Further localization fixes
Export as: Further cleanup
fr.po: Update by Jean Pierre
fr/Intro.lyx: Correction by Jean-Pierre
remove unused and error-prone function
Tufte examples: note how to add 'ols' option
Fix loop when trying to export a read-only document
Update it.po
Better icon for inset citation.

The previous one could be more easily associated to bookmarks rather
than to citations.
de.po: fix accelerator
InsetSpace and InsetVSpace are clickable (part of #8847)