add -fobjc-exceptions for compiling linkback sources with g++ and cmake on Mac
Original patch is from Ramanathan Vishnampet
Fix regression of 18779013 for \smash

When adding native support for \smash in 18779013 I overlooked that amsmath
redefines \smash to take an optional argument t or b. These optional
arguments are not parsed correctly anymore (bug 8967). This change fixes
the regression, so that \smash with optional argument appears in red, as it
was before th introduction of the native smash inset.
In the future, we should have native support for \smash[t] and \smash[b]
as well, but this would be a file format change (automatic amsmath loading),
and it is too late for 2.1.0.
Fix bug #4036 (lyx2lyx produces invalid LyX 1.4.x)

I should have had a closer look much earlier, since the fix is simple and
safe, but at that time I did not notice. The problem was that an invalid
.lyx document was created when converting unicode characters with two
backslashes in their LaTeX definition from lib/unicodesymbols to pre-unicode
LyX format.
Comment a minor bug not worth fixing (#8986)
stdtoolbars.inc: add icons for \xleftarrow.png

LyX supports \xleftarrow since years but an icon in the toolbar was missing
Forward search: add Enrico's comment from uses list.
ko.po, typo

Spotted by Dal Ho Park <airdalho@gmail.com>
remerge ko.po