logit transform volcano plots?

[alanocallaghan]

From workflow reviews. I think it looks better, although I see two issues:

1. Picking breaks. By default I've gone with 0.01, 0.1, 0.25, 0.5, 0.75, 0.9, 0.99, but this is arbitrary. Probably a great default, but we may want to be smarter at some point. Having said that, users can always xlim them afterwards if they really want to.
2. Any values exactly 0 or 1 are -Inf, Inf. To counteract this I've used a nudge function that sets these to the second-lowest value minus a bit (or the second-highest plus a bit). Means you don't get points way out in the distance distorting the range, but it is somewhat "dishonest".

Example plots from the workflow

• without logit:
• with logit:

[alanocallaghan]

Ah, looks like some points are being removed from the overdisp/resdisp panels in the logit example. Will investigate

[alanocallaghan]

Fixed versions:

• Without logit
• With logit

[alanocallaghan]

See branch logit-scale