Remove stale files

* stale being anything not in the list of project files which is in the
  list of git files that does not show up in a git grep. That gives a short
  list of files that were then sanity checked.

* Add madde_export.h to the relevant .pro-file while at it to stop it
  from showing up in the list mentioned above.

Change-Id: I787c88e08a45676bcdd256637339c630b1fa4b74
Reviewed-by: Daniel Molkentin <daniel.molkentin@nokia.com>