Bug 724241 - Internal inconsistency: namespace in IDL

Library was missing in the list of namespaces. In scanner.l constants, module and library are handled in the same way. In namespace.{h,cpp} only constants and module were handled, now also library is handled in a similar way.
Merge pull request #122 from albert-github/feature/bug_724241

Bug 724241 - Internal inconsistency: namespace in IDL