Add functionality to EM/GSEA integration - leading edge tool

[risserlin]

From a user:
I want to look at gene sets that have a positive NES and a low FDR - but in addition I want to select a further subset that met criteria from a related analysis (ie, a separate GSEA using the same modules). For leading edge analysis I simply manually selected the ones I wanted - but doesnt seem to be a way to do that w/ the for generating enrichment maps. Matching to a string would be nice

Interesting feature not from the EM side but from the mastermap side - show we the important genesets from analysis 1 and any genesets that also appear in analysis 2 (irrespective of whether it is significant in analysis 1).