[Dune] Constification day

[Thimo Neubauer]

Hi,

Christian and I decided that this Wednesday would suit us to include
the constification we decided on and to rename the methods with
underscores. Does anyone of you have large uncommitted changes? Or
should we move or plans to another day for other reasons?

During the changes we'll prepare a list of renames and send it around
so that you can adapt your code easily.

Cheers
  Thimo