Change x-axis label for volcano plot

[bnovotny]

Is your feature request related to a problem? Please describe.
Currently the volcano plot's x-axis label is set to "log2FC" but for my data the x-axis is actually showing the effects from linear models.

Describe the solution you'd like
The ability to specify the x-axis label for the volcano plot.

[ergonyc]

How many types of measures might we expect to see on the x-axis across data sets? If there's a few types we can enumerate them and have the type curated (or tested for)... if it could be alot we might need to have the label / scale as a "curated" with the data property.

Thoughts?

[bnovotny]

LogFC is definitely the most common, so perhaps a default to logFC with the option to curate a custom label? I don't know of a definitive list of possible x-axis measures, but I would be interested to hear others' thoughts as well.

[ergonyc]

@bnovotny @ricoderks just bumping this issue. I think it might be a good topic to quick cover in next weeks "brain trust"