Adding core of OrbitalStateDerivativeModel (Issue #703)

git-svn-id: file:///srv/svn/repos/tudat/trunk@558 ac7aa084-b6da-11df-bf42-7fac39f0224f
Adding FindPagmo script (Issue #757)

git-svn-id: file:///srv/svn/repos/tudat/trunk@559 ac7aa084-b6da-11df-bf42-7fac39f0224f