Refactor the multiple-comparisons arguments

[civilstat]

RankPlot() now has two arguments about multiple comparisons:
Bonferroni = c("none", "demi", "full")
and
multcomp.type = c("bonferroni", "independence")

The Bonferroni argument should be renamed to something like multcomp.scope for clarity.
This should be done in two stages -- first add a multcomp.scope argument and just deprecate the Bonferroni argument, then after a few months remove the Bonferroni argument entirely.

This also requires changing code in the vignettes.
We might as well add example plots using the Independence correction while we're at it.
And let's double-check whether the "full" corrections are correcting for (k choose 2) as I think it should, or for ((k-1) choose 2) as it says in the documentation.

[civilstat]

Also need to allow "none" as a multcomp.type option in RankColumnPlot() and FindSignifInColumn(), and add Adam Hall as a contributor.

[civilstat]

Mostly addressed by a recent commit.

But although RankColumnPlot() works, we still need to change the wrapper RankPlot() to allow multcomp.type != "demi" when plotType = "columns".

Also, we'll need to revisit this after a few version updates on CRAN have passed, and switch the Bonferroni argument from deprecated to defunct.

And still need to add example plots using the Independence correction to the vignettes.