CPACK_PACKAGING_INSTALL_PREFIX added to CMakeLists.txt

[MikePooh]

Before this commit CPack installs the files to default /usr/* directory and this caused problem with plugins searching

[dantti]

Doesn't it makes more sense to actually define a different CPACK_PACKAGING_INSTALL_PREFIX when you want to use cpack as the docs says each generator has it's own default..

[MikePooh]

I am not familiar with that. I've just met a problem - package made with cpack has install paths different from paths done with just 'make install'. In the first case it was /usr/* in second one it was /usr/local/*. It causes problems with plugin finding. Maybe there is better solution..