generate translation files for the Qt version automatically, if any

If translation files in .po format are present in ${src}/data/lang, .qm files will be generated automatically in the build directory, ready for installation during "make install".
The .po files can be downloaded by running the script "download-translations.bash" which also resides in ${src}/data/lang.

The motivation for this change is to simplify packaging for the Maemo5 version where the build system had to be patched for installation of translations.
suppress text selection
fix .desktop file
show decoration widget
FindQtMobility with components
QSystemInfo