richer aa test model
increase path uniformization maxNumJumps to 500
reinstate Variable.* and AbstractModelObject.* files
Improved MetropolisHastingsMove to handle general parent-child relationships
groundwork for NodeUniformizationSampleProposal.h
fixed bug in PathUniformizationSampleProposal where virtual events were not correctly destroyed
have basic NodeUniformizationSampleProposal working
added basic support for iid root freqs (will add Murray et al 2006 later)
Merge branch 'debug_mh' into development