Prepare build system for modern cmake (part 1)

To become independent from the FairRoot macros and scripts, simply add the needed macros in cmake/modules and input needed to generate the scripts into cmake/scripts.

Change copied macros such that the input needed to generate the scripts is taken from the local cmake/scripts directory.

Use macros and configuration input from local cmake directory.

Fix problem with removing the existing PATH and LD_LIBRARY_PATH variables when sourcing the config script without additional parameter.

cmake/modules/CbmMacros.cmake

@@ -180,7 +180,7 @@ MACRO (GENERATE_CBM_TEST_SCRIPT SCRIPT_FULL_NAME DEST_DIR)
 
   set(my_script_name ${SCRIPT_FULL_NAME})
 
-  configure_file(${FAIRROOTPATH}/share/fairbase/cmake/scripts/root_macro.sh.in
+  configure_file(${PROJECT_SOURCE_DIR}/cmake/scripts/root_macro.sh.in
                  ${DEST_DIR}/${shell_script_name}
                 )