Rename SceneContainer::countObjects() to countObjectsStrict().
Don't try to read $Server::MissionType from level info.
Try to fix SceneManager::scopeScene():

Size of box used to find potentially visible objects was computed incorrectly.
Change SceneObjectMasks and GameBaseMasks:

- Add GhostCleanupMask to SceneObject.
- Move RareStuffMask from GameBase to SceneObject and rename to RareUpdatesMask.
- Remove ScaleMask and FlagMask from SceneObject (use RareUpdatesMask instead).
Implement GhostCleanupMask in GameBase.
Make ShapeBase::processTick() call GameBase::processTick() to handle GhostCleanupMask.