Remove copyright notice from file header

It's not necessary to have the copyright notice available in all files.
It just takes time and effort to update. One file in the root directory
ought to be enough.

Signed-off-by: Marcus Karlsson <mk@acc.umu.se>
Bump copyright version year to 2013

Signed-off-by: Marcus Karlsson <mk@acc.umu.se>
Enable extra warnings as recommended by Xcode 4.6

As of Xcode 4.6 some extra compiler warnings are recommended. Take
advantage of them by enable them for the project.

Signed-off-by: Marcus Karlsson <mk@acc.umu.se>