IOPs are now compliant with -Wdouble-promotion

http://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-Wdouble-promotion-292
Fix da.po permissions.
Do not force anyone to use -Wdouble-promotion
introspection: Fix compile with clang-3.3

It seems that only oldish g++-4.6 doesn't like some of our generated
code (the part about initializing unions).
Fix a minor issue found by clang
Fix some memleaks found by cppcheck. Anything broken?
Merge branch 'double-promotion' of https://github.com/LebedevRI/darktable
Fix #9847: always fall back to file timestamp
Fix some memleaks from dt_conf_get_string()

That function returns a copy of the string that has to be g_free()'ed!
Write to stderr when browser couldn't be opened
Some more leaks: result of g_path_get_basename should be free'd
Experimental fix for crash(?) on dt exit, found by pmjdebru1jn
usleep is deprecated
[l10n] Swedish update
Fix capitals in strings
Revert "Do not force anyone to use -Wdouble-promotion"

This reverts commit a639dda521e09cb73a6711fd5e67a78a5e8dfe03.
Revert "IOPs are now compliant with -Wdouble-promotion"

This reverts commit f51a497795ea3856c20b68c0d24f5cc230db7e37.
Write less garbage to XMP files

The same should be done for the other rdf:Seq that might be empty.
2 more tiny leaks: g_strsplit
colorout: map shortkeys of gamut check/softproof to ctrl-g/ctrl-s

temporary fix for #9831