Moving IndependentCoalescentSampler to dr.evomodel.continuous

git-svn-id: http://beast-mcmc.googlecode.com/svn@6553 ca793f91-a31e-0410-b540-2769d408b6a1
Added Gaussian process interface for elliptical slice sampling

git-svn-id: http://beast-mcmc.googlecode.com/svn@6554 ca793f91-a31e-0410-b540-2769d408b6a1
Refactored LatentFactorModel and its parser so they do not depend on trees.

git-svn-id: http://beast-mcmc.googlecode.com/svn@6555 ca793f91-a31e-0410-b540-2769d408b6a1