EntityManager: Split out PerformScan

Start breaking down the code so regular people can comprehend it.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Change-Id: I82fec105fbe29bd09145feaaa48fbcb875ca930f
diff --git a/src/meson.build b/src/meson.build
index 8a9811b..bab416c 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -3,6 +3,7 @@
 executable(
     'entity-manager',
     'EntityManager.cpp',
+    'PerformScan.cpp',
     'Overlay.cpp',
     'Utils.cpp',
     cpp_args: cpp_args + ['-DBOOST_ASIO_DISABLE_THREADS'],