Better control of Circos chromosomes

[alancleary]

Currently the Circos plots only contain the chromosomes of the query tracks in the micro-synteny view. This is because including all chromosomes from the result tracks may be too computationally heavy when many results are present. Users can get around this by selecting one of more of the result tracks to be query tracks in a new micro-synteny view. However, this method is not intuitive. A more reasonable approach would be to allow users to specify what chromosomes they want to make a plot for without having to load a new micro-synteny view. Make it so!