2.12.6:

* Container: Avoid a useless warning about remove() with custom containers.
  (Murray Cumming) Bug #518002 (Jonathon Jongsma).	
* Build: Fixed a warning from g++ 4.3.
  (Tim Retout) Bug #524874.
* Documentation: Correct the debian/Ubuntu package name.
  (Deng Xiyue)