Build: added support for unity builds in most projects except for StormLib, ZLib and Scripts

dep/g3dlite/CMakeLists.txt

@@ -71,3 +71,12 @@ set_target_properties(g3dlib
     PROPERTIES
       FOLDER
         "dep")
+
+if(UNITY_BUILDS)
+  set_target_properties(g3dlib
+      PROPERTIES UNITY_BUILD ON)
+  set_target_properties(g3dlib
+      PROPERTIES
+        UNITY_BUILD_MODE BATCH
+        UNITY_BUILD_BATCH_SIZE 8)
+endif()