Reformat CMakeLists.txt

Author: sami-hatna66

external/CMakeLists.txt

@@ -1 +1,11 @@
-add_library(external Actor.cpp Room.cpp Path.cpp MathHelper.cpp DifferentialEq.cpp VectorMaths.cpp Heatmap.cpp ParseInputFile.cpp RandomNumber.cpp Stats.cpp)
+add_library(external Actor.cpp 
+                     Room.cpp 
+                     Path.cpp 
+                     MathHelper.cpp 
+                     DifferentialEq.cpp 
+                     VectorMaths.cpp 
+                     Heatmap.cpp 
+                     ParseInputFile.cpp 
+                     RandomNumber.cpp 
+                     Stats.cpp
+            )