Make the runtime reflection API for names, modules, locations more systematic

Currently in base we have

• GHC.SrcLoc: the data type SrcLoc contains srcLocPackage and srcLocModule
• Data.Typeable.Internals: the data type TyCon contains tyConPackage, tyConModule and tyConName.
• GHC.Generics: the data type Datatype contains dataTypePackage, dataTypeModule and dataTypeName
• Data.Data: the data type DataType (yes the capitalisation differs!) contains a field tycon :: String, and there are functions tyconModule :: String -> String, and tyconUQname :: String -> String, for parsing that string and extracting the module name and tycon name.
• GHC.StaticPtr: the data type StaticPtrInfo contains spInfoPackageKey, spInfoModuleName, spInfoName (all Strings). Oh, and spInfoSrcLoc :: (Int,Int) too!
• GHC.Stack.ccSrcSpan :: Ptr CostCentre -> IO CString stores a source location in a C structure, and returns it as a CString.

This is madness! Six different representations for the same information in one package!

Let's fix this by defining some shared data types, for

• Module = ModuleName + package
• Entity = Module + unqualified name

There would be a tiresome changeover period; but Typeable and StaticPtr are in flux anyway.

Would anyone be willing to lead on this?