ggdist: Visualizations of distributions and uncertainty

Major changes:

• The geom_slabinterval() and geom_dotsinterval() families gain "sub-guides", which can be passed to the subguide parameter to create axis annotations for the thickness aesthetic (for slabs) and the dot count (for dots) (#183).
• The weight aesthetic is now supported in stat_slabinterval(), including weighted calculations for densities, CDFs, all interval types (quantile intervals, highest density intervals, and highest density continuous intervals), and all point summaries (mean, median, and mode) (#41). This includes support for the upcoming weighted random variable type in the posterior package.
• Blurry dotplots are now supported using geom_blur_dots(), which accepts an sd aesthetic to set the standard deviation of the blur on each dot. Intervals can also be used in place of blur by passing blur = "interval". This geom is used by the new stat_mcse_dots() to show quantiles along with their error using blur (#63).
• The new breaks_quantiles() histogram breaks function allows the construction of quantile histograms with density_histogram(), stat_histinterval(), etc.
• The color ramp scales (e.g. scale_colour_ramp_continuous(), ...) now use an explicit data type, partial_colour_ramp(), to encode color ramps and their origin colors, and provide the ramp_colours() function for applying colour ramps. This should make it easier to pass explicit color ramps without using scale functions, and for packages building on {ggdist} to use the colour ramp scales (#209).

Minor changes:

• The default histogram bin selection algorithm is now "Scott" instead of "Sturges", as "Sturges" tends to be too conservative (#214).
• The at parameter to stat_spike() (or its names) now determines values of an at computed variable, which can be mapped onto aesthetics via after_stat() to more easily label spikes. (#203; thanks @mattansb for the suggestion).
• The arrow parameter is now supported for intervals in geom_slabinterval() (#206; thanks to @ASKurz for the suggestion).
• The default value of overflow in geom_dotsinterval() is now the new "warn" mode, which works the same as "keep" except that it warns users if the dots will overflow the geometry bounds and suggests solutions (#213).
• Optional arguments to automatically partially-applied functions can now be passed a waiver() to use their default value (see auto_partial()).
• Several dependency reductions: removed {cowplot}, {purrr}, {forcats}, {palmerpenguins}, and {modelr} from Suggests; moved {tidyselect} and {dplyr} from Imports to Suggests. The latter two are only strictly necessary for curve_interval() due to its use of grouped data frames and tidy selection to specify which columns are conditional and which are joint (the use of grouped data frames with point_interval() is less strictly necessary, and not used by stats, so is easier to avoid as an absolute dependency).

Documentation:

• The pkgdown documentation now includes an online article on the thickness aesthetic with comprehensive examples of how slab scaling works (#205).

Bug fixes:

• Ensure Mode() works on analytical constant distributions.
• Various fixes to ensure compatibility with {ggplot2} 3.5.0.