Fix json_spirit weird Boost dependency problem with Debug libraries.
Current Time available as a public attribute of Game class.
Merge branch 'time' into develop
Updatd install instructions.

New libraries added to the description and OS X steps simplified thanks to homebrew.
Merge branch 'doc' into develop
Fix problem with relative paths to resources.

Only OS X is fixed, Linux and Windows needs a solution.
Merge branch 'hotfix' into develop
Fix problem with Mac Path.
Merge branch 'develop'