Changeset 5648 for code/branches/libraries/src/orxonox/objects/quest/notifications/NotificationOverlay.cc

sorry, large commit, but all changes are dependent:

• Created a new plugin for the questsystem (called just "quest" for the moment because I'd had to rename the directory otherwise (the tolua script enforces this))
• Added QuestPrereqs.h file and _QuestExport macro
• Moved the GUI-name ↔ PlayerInfo map from QuestManager to GUIManager
• Moved NotificationOverlay and NotificationQueue from overlays to quest and linked the overlays plugin into the quest plugin
• Made QuestManager and NotificationManager ScopedSingletons with ScopeID GSLevel. Also removed both singletons from GSLevel and added the Scope instance instead.