Refactor cmake (#721)

* some start of refactor

* Update SetFlags.cmake

* Update SetCmakeVar.cmake

* Update SetFlags.cmake

* Fix error int-convertion

* more refactor

* clean up include and source file

* fix link of lib

* fix a warning

* fix include in src/actors

* fix include in src/debug

* fix include in src/ending

* fix include in src/engine/actors

* fix include in src/engine/cameras

* fix include in src/engine/editor

* fix include in src/engine/objects

* fix include in src/engine/tracks

* fix include in src/port/ui

* fix include in src/racing

* fix include in src/engine/vehicles

* fix include in subfolder of src/engine

* fix include in src/engine

* fix include in src/enhancements

* fix include in src

* fix switch

* invert common and findlib

* Update SetFlags.cmake

* clean up some workflow

* some splification

* Update build.sh

* Update Game.h

* add header back

* Delete test_check.cmake

* continue

* Update common.cmake

src/engine/RaceManager.cpp

@@ -8,7 +8,7 @@
 #include "engine/RandomItemTable.h"
 
 extern "C" {
-#include "render_courses.h"
+#include "racing/render_courses.h"
 }
 
 RaceManager::RaceManager(World& world) : WorldContext(world) {