Import update of lensfun to 0.2.7.
Upcoming Digikam 3.0.0 requires lensfun>=0.2.6.
Unbreak library by providing two missing functions.
Add WCSLib, optional dependency of KStars.
Digikam 3.0.0 & Co.
Oops, didn't intended to commit that bit of Digikam port Makefile.
Import update for CMake; two additions:

  * Add FindBacktrace.cmake, a module searching for backtrace() implementation.
  * Add arch-specific dirs to search paths. Ruby 1.9 does not support them in
    RbConfig, 2.0 do but it's probably don't worth backporting. So this patch
    is not intended to go upstream but it unbreaks at least
    kross-interpreters from KDE 4.
KDE 4.10.0 progress, almost done.