Finished tdogle::Camera class
Article 04 finished on OSX
Whoops, tdogl::Camera::up was returning downwards
More consistent use of constants
Article 04 done on windows
Updated readme for article 4
Added 04_camera for GNU/Linux.
Project was missing for article 04 on OSX

the gitignore file isn't working as I expected it to
Fixed gitignore for xcode projs