Added ability to load earlier BEAUti files (even if they were missing components later added).

git-svn-id: http://beast-mcmc.googlecode.com/svn@6539 ca793f91-a31e-0410-b540-2769d408b6a1
Info logger didn't have a handler for warnings and errors so these weren't being shown.

git-svn-id: http://beast-mcmc.googlecode.com/svn@6540 ca793f91-a31e-0410-b540-2769d408b6a1