Fix formatting of code example in docs.
Reorganise libraries in openorbit repo.

Libvmath is now tracked in its own repository. This needs to be checked out into
lib/vmath.

Libcelmek should be checked out into lib/celmek.

Adding xcode workspace as umbrella for openorbit, vmath and celmek.
Merge pull request #12 from lorrden/master

Use libvmath from vmath repo in openorbit