SW-826: adding Casacore.casa as dependency on LCS/Common makes many lofar libs dependend on 3rd party libs which we don't actually use. This hinders us in deployment and maintenance on various systems. However... apparently many packages depend on this dependency, so here it is again.  

SW-826: adding Casacore.casa as dependency on LCS/Common makes many lofar libs dependend on 3rd party libs which we don't actually use. This hinders us in deployment and maintenance on various systems. Hence, I removed the hard dependency on Casacore.casa, and made the empty-stub-CasaLogSink print out a warning message.

Task #2699, #514: Moved share directory containing clusterdesc files from LCS/Common to CEP/LMWCommon

First version

Added clusterdesc files

easy access to a package's source/binary directory. This is now
handled by lofar_add_package().

- New lofar_package() macro replaces lofar_add_package(). The new macro
  supports recursive addition of LOFAR packages, using the dependencies passed
  as arguments. For example: 
    lofar_package(Blob 1.0 DEPENDS Common) 
  will add the package Common to the build (unless it was already added).
  This new features enables a "top-down" package specification order, which is
  required for building subsystems.

- New lofar_add_package() macro replaces lofar_add_subdirectory(). This macro
  uses a ${pkg}_SOURCE_DIR variable to locate the source directory of the
  package <pkg>. This information is needed, as we cannot simply include
  actual subdirectories anymore, because dependent package(s) might be located
  in a different directory tree.

- New file LofarPackageList.cmake, which sets the ${pkg}_SOURCE_DIR variables.
  This file is generated by a script gen_LofarPackageList_cmake.sh, which must
  be rerun when LOFAR packages are added, moved, or removed.

* Added APLCommon to the CMake build.
* Use of INCLUDE_PATH_SUFFIX is now optional.
* Removed EXCLUDE_FROM_ALL from add_subdirectory(test).

branch LOFAR-Bug1310-task-branch with the trunk.

rev. 12447-13413 with the trunk.