This function takes a TockyPrepData object, which should have been previously
processed using the timer_transform function, and creates a ridge plot showing
the density distribution of angles for each group defined in the dataset.
Arguments
- x
 A TockyPrepData object that has been processed with the
timer_transformfunction.- alpha
 A number between 0 and 1 to be usedby ggridges.
- group_order
 Optional. A character vector to define the order of group
- scale
 A scaling factor to scale the height of the ridgelines. Used by ggridges.
- legend
 Logical. If TRUE, legend is included.