return a new GeneAnswers instance with sorted by the specified type.
Details
sortBy could be one of "geneNum", "pvalue", "foldChange", "oddsRatio" and "correctedPvalue".
References
Feng, G., Du, P., Krett, N., Tessel, M., Rosen, S., Kibbe, W.A. and Lin, S.M., 'A collection of bioconductor methods to visualize gene-list annotations', BMC Research Notes 2010, 3:10