cpack.d is a dropin directory for cmake/cpack, decoupling os specific 
packaging rules from project code development.

Every CPack template file (postfixed with '*.cmake.in') in the directory,
is automatically configured during the usual cmake project building.

The resulting CPack files will be available in the corresponding binary 
directory (postfixed with '*.cmake') and usable as cpack configs.

`cpack --config <build root>/cpack.d/<config-name>.cmake`

The existing templates will produce packages with:

 * package names compliant with the target OS rules
 * build number equal to the number of commits on the current branch
 * stripped binaries
 * support for runtime, development and documentation components

The commons.cmake.in extracts CMake project specific attributes and prepare 
them to be used by the os specific package configs through the invocation of 
the macro 'config_package'.

Project specific settings, like the description summary, are fetched
from an external directory passed during the invocation of the 'config_package' 
macro via the DATA argument.