Math.lyx: describe new support for command \sideset
Math.lyx: describe new support for \hspace* etc.
Fix key bindings for math space (#8974)
UserGuide.lyx: describe new supported negative spaces
Math.lyx: update description for command \mathclap
It's definitely not safe to continue in this case. The cursor is
invalid. So we should try to save the document before anything
really bad happens.
Math.lyx: describe command \adjustlimits
UserGuide.lyx: describe new support for \listoflistings
csv2lyx: use universal newlines when reading CSVs

Patch from Dustin J. Mitchell.
Simplification
Fix localization of captions (#8977)
UserGuide.lyx: fix some shortcut issues after [ea8248fc/lyxgit]

- German UserGuide.lyx: add missing image showing the abstract environment
Math.lyx: use inset-info instead of images for LyX-icons (part 1)
Math.lyx: use inset-info instead of images for LyX-icons (part 2)

- also add info about special relations
cua.bind, math.bind: whitespace fixes: use consistently tabulators
UserGuide.lyx: correct some text styles

- German UserGuide.lyx: update some outdated info
UserGuide.lyx: correct more text styles
UserGuide.lyx: correct more text styles (hopefully now all)

- German UserGuide.lyx: add missing index entry
stdmenus.inc: correct 2 expressions
Math.lyx: use inset-info instead of images for LyX-icons (final part)

- Japanese Math.lyx: correct an image path