Pathway Bar plots should be able to select arbitrary gene sets#1

In the Braid plot UI, it's possible to choose a gene set, but also individual genes (see second tab) <img width="378" alt="screen shot 2018-09-14 at 4 29 51 pm" src="https://user-images.githubusercontent.com/2761597/45573715-7af11000-b83b-11e8-99f0-d5d01718d320.png"> If you choose a gene set, those genes in the set populate the genes tab. You can then add or subtract genes that interest you. <img width="380" alt="screen shot 2018-09-14 at 4 30 01 pm" src="https://user-images.githubusercontent.com/2761597/45573716-7af11000-b83b-11e8-8b6b-71d4b8e406ce.png"> I devised this feature after having finished the pathway bar plot. The bar plot is custom-built for 3 specific datasets: <img width="376" alt="screen shot 2018-09-14 at 4 31 43 pm" src="https://user-images.githubusercontent.com/2761597/45573799-b8559d80-b83b-11e8-8be1-6aebf07c2fe7.png"> Now that we're "polymorph-izing" pathway bar plots, it makes sense to replace those other tabs with useful functions, assuming a single dataset. The first obvious such tab is "Genes". - It should be possible to select an arbitrary gene list and see those genes in the bar plot. - It should also be possible to select a pathway and the genes in that pathway show up in the genes tab. - Finally, it should be possible to edit those genes in the gene tab that were populated by selecting a pathway.