build: Fix CMake and ns3 script bugs, add a test suite and fix formatting

examples/matrix-topology/CMakeLists.txt

@@ -1,5 +1,9 @@
 set(name matrix-topology)
 set(source_files ${name}.cc)
 set(header_files)
-set(libraries_to_link ${libnetwork} ${libnetanim} ${libmobility} ${libpoint-to-point} ${libinternet} ${libapplications})
-build_example("${name}" "${source_files}" "${header_files}" "${libraries_to_link}")
+set(libraries_to_link ${libnetwork} ${libnetanim} ${libmobility}
+                      ${libpoint-to-point} ${libinternet} ${libapplications}
+)
+build_example(
+  "${name}" "${source_files}" "${header_files}" "${libraries_to_link}"
+)