DeclIt_t to TClass* map to have access to TClass* without name search. (ROOT-6159).
Add/remove the DeclId-TClass pointer pair to the map when a TClass is added/removed.(ROOT-6159).
Remove trailing space.
Check for TClingClassInfo not Null when adding to the map and change constant for more than one class in the map with same DeclId. (ROOT-6159).
Move DeclIdMap_t to ROOT and suppres unused parameters for TClass::GetClass. (ROOT-6159).
Add comments, remove unused code. (ROOT - 6159).