add alternate model summary

This adds an alternate model summary that "more correctly" show the model
statuses at the cost of running significantly slower.  The old summary is
still available with the `--fast-model-summary` option.

Old:

Genome::Model::ReferenceAlignment
         Failed 1
        Running 37
    Unstartable 18
          Total 56

New:

Genome::Model::ReferenceAlignment
   Build Needed 30
        Running 26
          Total 56

----

Should we default to the "inaccurate" fast method instead of the "accurate"
slow method?  Should we try to make Genome::Model::status faster by using
hand-writtern SQL?  Does that need to be part of this PR?  In the example
"significantly slower" meant ~10 seconds instead of ~3.5 seconds and would get
worse for larger AnP.